The chamber cleared Tillerson by a 56-to-43 vote, largely along party lines. He needed a majority of 51.
The vote confirms a key official in the Trump administration in what has been a grind for his Cabinet choices. Trump's Cabinet has filled out slowly amid Democratic opposition to many of his nominees.
Tillerson's critics had seized on his business dealings in Russia while at Exxon and his lack of government experience. But the White House and his supporters in the Senate touted his experience making business deals around the globe as evidence that he could represent U.S. interests abroad.
The intelligence community's conclusion that Russia tried to interfere in the 2016 U.S. election — and Trump's reluctance to accept it — intensified the rhetoric surrounding Tillerson. Key Republicans Marco Rubio of Florida, John McCain of Arizona and Lindsey Graham of South Carolina initially said they were skeptical of Tillerson before backtracking and supporting him, despite reservations about some of his Russia-related answers.
Some lawmakers raised concerns that Tillerson could lift sanctions on Russia related to its 2014 annexation of the Crimea region in Eastern Ukraine. Trump has not outright committed to removing those sanctions, but has said he wants a better relationship with Russian President Vladimir Putin.
Democrats also raised concerns about possible conflicts of interest in decisions that could affect Exxon. Tillerson previously divested from his stake in the company.