The former ExxonMobil chief spent seven hours with legislators and staffers from the House Foreign Affairs Committee, the Washington Post reported.
A Tillerson spokesperson told the news outlet that the meeting "covered a wide array of topics related to foreign affairs, the operations of the nation’s foreign policymaking apparatus and his tenure as Secretary of State."
The White House reportedly knew of the meeting, which was requested by Rep. Eliot L. Engel, D-N.Y., but did not attempt to stop it.
Tillerson, 67, a native of Texas, served as President Trump's first secretary of state from February 2017 until the president ousted him, via Twitter, in March 2018.
Both Tillerson and Trump had a strained relationship. Tillerson said during a fundraiser the two did not share a "common value system" and were "obviously starkly different in our styles."
“When the president would say, ‘Here's what I want to do, and here's how I want to do it,’ and I'd have to say to him, ‘Well, Mr. President, I understand what you want to do, but you can't do it that way. It violates the law, it violates the treaty, you know. He got really frustrated,” Tillerson said. “I think he grew tired of me being the guy every day who told him he can’t do that and let’s talk about what he can do.”
Tillerson said he told Trump he would be willing to “fight the fight” to change laws in Congress so the president could press forward with his agenda.
Trump, in return, called Tillerson "dumb as a rock" and "lazy as hell," and tweeted that he couldn't get rid of his secretary of state "fast enough."