Tillerson said the president had spoken with him, but not until hours later.
'I received a call today from the President of the United States a little after noontime from Air Force One,' he said.
'I've also spoken to White House Chief of Staff Kelly to ensure we have clarity as to the days ahead.'
The shaken-sounding former cabinet secretary told reporters that his official ending date will be March 31, and that he aims for an 'orderly and smooth transition' for his replacement, CIA Director Mike Pompeo.
Deputy Secretary of State John Sullivan will assume Tillerson's duties at midnight tonight.
Trump fired Tillerson on Tuesday without telling him personally, announcing on Twitter that he would dismiss him and elevate the nation's spymaster to the role of global diplomat-in-chief.
And he said he will appoint a woman to lead the CIA for the first time in history.
Under Secretary of State for Public Diplomacy and Public Affairs Steven Goldstein said in a statement that Tillerson had 'had every intention of staying.'
'The Secretary did not speak to the President and is unaware of the reason, but he is grateful for the opportunity to serve,' Goldstein added.
SCROLL DOWN FOR VIDEO
Rex Tillerson is pictured leaving his home on Tuesday, en route to the State Department for what would be his last morning as secretary of state
This is on me: Trump used twitter to terminate the career of Rex Tillerson, the former Exxon Mobil boss who had been secretary of state for 15 months. An official revealed the president did not speak to Tillerson
You're fired: Rex Tillerson was abruptly fired by Donald Trump on Tuesday morning in a single tweet
Replacement: Mike Pompeo, who had been CIA director, will now lead the State Department and Gina Haspel, a career CIA officer who was its deputy director will become the first woman to lead it
Family: Rex Tillerson had stepped down as CEO of Exxon Mobil when he was offered the job by Trump. His wife Renda St. Clair persuaded him to take it saying: 'I told you God's not through with you.'
He was later fired himself for departing from the official White House line – which was that Trump had told Tillerson on Friday that he would be leaving.
Tillerson's last public act had been firmly blaming Russia for the poisoning of a former spy and his daughter - which the White House had pointedly avoided saying was carried out by Vladimir Putin's government.
As he left the White House for a trip to California , Trump told reporters that he and Tillerson had been 'talking about this for a long time' but that he 'made the decision by myself.'
'We disagreed on things,' Trump said, citing the Obama-era nuclear agreement with Iran. 'I think Rex will be much happier now,' he declared.
'We were not really thinking the same. With Mike, Mike Pompeo, we have a very similar thought process. I think it's going to go very well.'
Trump made no mention of the most notorious tussle between him and Tillerson, when the secretary of state was reported to have called the president a 'f***ing moron' then refused to deny it.
The State Department said Tillerson only learned of his termination when he read Trump's tweet on Tuesday morning.
YOU'RE ALL FIRED: TRUMP'S ASTONISHING LIST OF SENIOR DEPARTURES
Who went and when:
March 13: Secretary of State Rex Tillerson
March 12: Special assistant and personal aide to the president John McEntee
March 6, 2018: Economic adviser Gary Cohn
Feb. 28, 2018: Communications director Hope Hicks
Feb. 27, 2018: Deputy communications director Josh Raffel
Feb. 7, 2018: Staff secretary Rob Porter
Dec. 13, 2017: Communications director for the White House Office of Public Liaison Omarosa Manigault Newman
Dec. 8, 2017: Deputy national security adviser Dina Powell
Sept. 29, 2017: Health and Human Services Secretary Tom Price
Aug. 25, 2017: National security aide Sebastian Gorka
Aug. 18, 2017: Chief strategist Steve Bannon
July 31, 2017: Communications director Anthony Scaramucci
July 28, 2017: Chief of staff Reince Priebus
July 21, 2017: Press secretary Sean Spicer
May 30, 2017: Communications director Michael Dubke
May 9, 2017: FBI Director James Comey
March 30, 2017: Deputy chief of staff Katie Walsh
Feb. 13, 2017: National security adviser Michael Flynn
Two senior department officials said Tillerson received a call from John Kelly, Trump's chief of staff, on Friday, but was only told that there might be a presidential tweet that would concern him.
Kelly didn't tell Tillerson what the tweet might say or when it might actually publish, according to the official, who wasn't authorized to speak publicly on the matter and demanded anonymity.
Tillerson had told reporters on his plane he had cut short his trip by one night because he was exhausted after working most of the night two nights in a row and getting sick in Ethiopia.
There were no obvious signs from his behavior or his aides on the plane that his departure was imminent.
'I felt like, look, I just need to get back,' Tillerson said.
Instead he was fired and left to spend time with his wife, Renda St. Clair, who had told him to take the job when he was reluctant to himself.
He had revealed last year how when Trump offered him the role 'I was going to the ranch to be with my grandkids.'
Instead his wife shook her finger in his face and told him: 'I told you God's not through with you.'
But by last week Trump was through with Tillerson instead.
One senior White House official said that when Trump made the dramatic and sudden decision last Friday to meet with Kim Jong Un - a decision made while Tillerson was in Africa - an aide asked if Tillerson should weigh in on the matter.
Trump said there was no reason to consult him because no matter what the group decided, Tillerson would be against it, the official said.
On the White House lawn Trump gushed that his future secretary Mike Pompeo has 'tremendous energy, tremendous intellect, we're always on the same wavelength. The relationship has been very good.'
The president had tweeted earlier that Pompeo 'will do a fantastic job!'
'Thank you to Rex Tillerson for his service! Gina Haspel will become the new Director of the CIA, and the first woman so chosen. Congratulations to all!'
Haspel was the CIA's deputy director, a career officer who was a longtime clandestine officer.
She was involved in running a black site during the notorious CIA detention program which saw prisoners waterboarded, and could face a highly rocky confirmation hearing in front of the Senate.
Haspel, 61, was the boss of a prison in Thailand codenamed Cat's Eye where al Qaeda suspects were held., including Abu Zubatdah, who was waterboarded 83 times in a month, sleep deprived and lost his left eye.
She also ordered the destruction of tapes from the facility and when she was appointed deputy CIA director, Democratic senators on the Senate Intelligence Committee urged Trump to reconsider his decision, setting up a confrontational confirmation hearing.
Victim: Sergei Skripal and his daughter Yulia were poisoned in a pizza restaurant in Salisbury, in south-west England and Rex Tillerson publicly blamed Vladimir Putin's Russia for the attack on Monday, something the White House had pointedly not done
Key figure: Trump repeatedly crossed swords with Rex Tillerson, including a public episode in October where the president chided him on Twitter for 'wasting his time trying to negotiate with Little Rocket Man' – a reference to North Korean dictator Kim Jong-Un - which Trump is now going to do face-to-face
In a statement, Trump said Pompeo 'graduated first in his class at West Point, served with distinction in the U.S. Army, and graduated with Honors from Harvard Law School. He went on to serve in the U.S. House of Representatives with a proven record of working across the aisle.'
He called Haspel's move to the CIA's reins 'a historic milestone.'
Trump also had words of praise for Tillerson: 'A great deal has been accomplished over the last fourteen months, and I wish him and his family well,' he said.
The president, however, had clashed with Tillerson over and over again in the past year, seeing him as a relic of the Republican establishment at a time when the nation needed more unconventional thinking.
The Washington Post reported that Tillerson was ousted on Friday, meaning that the White House known best for leaking information kept it a secret all weekend.
The outgoing diplomat's last act in office was a shot across Vladimir Putin's bow, saying Monday that the poisoning of an ex-Russian spy in the UK 'clearly came from Russia' – and vowing to respond – hours after the White House refused to blame the Kremlin.
In a strongly worded statement, he slammed Russia as an 'irresponsible force of instability in the world' and gave the British government his backing after Prime Minister Theresa May pointed her own finger toward Moscow.
'We have full confidence in the UK's investigation and its assessment that Russia was likely responsible for the nerve agent attack that took place in Salisbury last week,' Tillerson said Monday.
Final meeting: Nigerian president Muhammadu Buhari was the last world leader to receive Tillerson as he wrapped up a swing through Africa
Goodbye: Rex Tillerson was last seen on Monday boarding his plane home to the United States after a tour of Africa which concluded in Abuja, Nigeria, after taking in countries including Ethiopia and Kenya
Downhill from here: Rex Tillerson was sworn in by Mike Pence in the Oval Office on February 1 2017, with his wife Renda St. Clair holding the Bible. She had told him to take the job over his own reluctance
Family time: There was no sign of Rex Tillerson at hiss home in D.C.'s upscale Kalorama Tuesday. Also fired was Steven Goldstein, under secretary of state for public affairs who revealed Tillerson had been blindsided by his firing - then got axed himself
Simulation: Some of the 'enhanced interrogation techniques' used at the CIA 'black site' run by Trump's pick to direct it were shown on Zero Dark Thirty, the movie about the hunt for bin Laden
'There is never a justification for this type of attack, the attempted murder of a private citizen on the soil of a sovereign nation, and we are outraged that Russia appears to have again engaged in such behavior.
'Russia continues to be an irresponsible force of instability in the world, acting with open disregard for the sovereignty of other states and the life of their citizens.'
He added that those responsible 'must face appropriately serious consequences.'
Trump seemed to back him up on Tuesday, saying that he would be speaking with May later in the day.
'It sounds to me like it would be Russia,' he said, 'based on all of the evidence that they have.'
Tillerson made the remarks during his trip to Africa just hours after the the White House broke a week-long silence to condemn the chemical attack, but declined to mention Moscow.'
Trump had repeatedly crossed swords with the former Exxon Mobil executive, including a public episode in October where the president chided him on Twitter for 'wasting his time trying to negotiate with Little Rocket Man' – a reference to North Korean dictator Kim Jong-Un.
Foreign policy veterans said at the time that they couldn't recall an instance where a sitting president had undermined his secretary of state in such a humiliating fashion.
Lost an eye: Abu Zubaydah was one of those subjected to 'enhanced interrogation techniques' which critics called torture. He was waterboarded 83 times and lost an eye
But five months later the president himself accepted Kim's invitation for a face-to-face meeting over the hermit kingdom's nuclear missile program.
Tillerson raised eyebrows in Washington last year with reports that he had called Trump a 'moron' following a national security meeting in July about America's nuclear posture.
He never directly denied making the caustic remark, leaving that to a State Department spokeswoman. Trump said the same day that he had 'total confidence in Rex.'
Later that month, newly installed White House Chief of Staff John Kelly and Secretary of Defense James Mattis begged Tillerson to stay on.
The following month, after Trump angered Americans on both sides of the aisle with tone-deaf comments about the role of neo-Nazis in a Virginia race riot, a furious Tillerson declined to defend him.
'The president speaks for himself,' Tillerson said at the time during a 'Fox News Sunday' interview.
Even then, the White House outwardly professed comfort with Tillerson and confidence in his abilities.
Haspel will need to face a Senate confirmation hearing.
Pompeo will not – at least not right away – because the Senate confirmed him as the CIA director just three days into the Trump administration.
A different committee will ultimately have to grill him, however.
Trump said that his incoming secretary of state 'has earned the praise of members in both parties by strengthening our intelligence gathering, modernizing our defensive and offensive capabilities, and building close ties with our friends and allies in the international intelligence community.'
'I have gotten to know Mike very well over the past 14 months, and I am confident he is the right person for the job at this critical juncture,' he added.
'He will continue our program of restoring America's standing in the world, strengthening our alliances, confronting our adversaries, and seeking the denuclearization of the Korean Peninsula.'
MIKE POMPEO, TRUMP'S NEW SECRETARY OF STATE, PURSUED HILLARY AND JOKED ABOUT ASSASSINATING KIM JONG-UN
Mike Pompeo, named Tuesday to be US secretary of state, comes from a one-year stint leading the Central Intelligence Agency where he earned Donald Trump's trust delivering the president's daily national security briefings and by toeing Trump's line politically.
Pompeo, who replaces Rex Tillerson, brings the discipline of a former standout at West Point, the prestigious US military academy, as well as the political wiles of a four-term member of the House of Representatives, where he served on the controversial Intelligence Committee.
AS CIA director he cut a path into Trump's inner circle with ready praise of the president, personally delivering many of the Oval Office's crucial daily intelligence briefings.
He echoes Trump's hard line against Iran and North Korea. But, currying the president's favor, Pompeo has also avoided directly contradicting Trump's insistence that Russia did not work to support his election in 2016 -- even though that is what the CIA concludes.
'With Mike Pompeo, we have a very similar thought process,' Trump said Tuesday.
Pompeo, 54, has had a meteoric career that leaned heavily on political opportunities that ultimately led him to Trump.
Born and raised in southern California, he attended the US Military Academy at West Point, where he graduated top of his class in 1986, specializing in engineering.
He served in the military for five years - never in combat - and then left to attend Harvard Law School.
He later founded an engineering company in Wichita, Kansas, where financial backers included the conservative Koch brothers, oil industry billionaires and powerful movers and shakers in the Republican Party.
Pursuit: Pompeo made his name going after Hillary Clinton as a member of special committee formed to investigate the 2012 killing of a US ambassador and three other Americans in Benghazi, Libya.
The Kochs backed his successful first run for Congress in 2010, and energy-related legislation he promoted in his first years in the House of Representatives was seen as very friendly to them.
He moved quickly onto the House Intelligence Committee, where, as overseer of the CIA and other agencies, he was privy to the country's deepest secrets.
But he made his name on the special committee Republicans formed to investigate the 2012 killing of a US ambassador and three other Americans in Benghazi, Libya.
It made him a leading voice against Trump's political nemesis, Hillary Clinton, who as secretary of state at the time was blamed by Republicans for the deaths.
As director of the CIA, Pompeo has matched the tone of Trump's foreign policy pronouncements.
'The CIA, to be successful, must be aggressive, vicious, unforgiving, relentless,' he said.
He joked about assassinating North Korean leader Kim Jong Un, which raised fears of a return to the agency's penchant for backing assassinations of dictators not in US favor.
He earned the president's trust in the daily national security briefings, where he has readily accommodated the president's aversion to reading long reports by having intelligence staff prepare simple graphic presentations of global risks and threats.
When pressed in public, he has said he supports the January 2017 report by the country's top intelligence chiefs that concludes that Russia meddled in the 2016 presidential race in an effort to help Trump defeat Clinton.
Meanwhile, he has also stomached the president's ugly attacks on the CIA, calling their report on Russia meddling fake news and accusing them of political bias.