It was the closest vote on a Supreme Court Justice since 1881, when the Senate approved Justice Stanley Matthews by a vote of 24-23.
While Republicans rallied behind the judge, Democrats said Kavanaugh's elevation to the Supreme Court was a mistake.
"He's shown he cannot be trusted to tell the truth," said Sen. Patrick Leahy (D-VT), as Democrats denounced what they said was a truncated FBI review of allegations leveled against Kavanaugh.
"Judge Kavanaugh’s record is clear," said Sen. Sherrod Brown (D-OH). "He has consistently sided with the most powerful special interests, not American workers."
"Kavanaugh has made it very clear to the American people that he is biased and perceives things through the lens of a partisan operative," said Sen. Kamala Harris (D-CA).
"We have to mourn the lack of seriousness the Senate showed toward credible allegations of sexual assault," said Sen. Tim Kaine (D-VA).
"Judge Kavanaugh's testimony was partisan, evasive, and on many points under oath, even untruthful," said Sen. Chris Van Hollen (D-MD).
As Van Hollen spoke on a hushed Senate floor, hundreds of demonstrators rushed onto the central steps of the Capitol, breaking through crowd control barriers which had sealed off part of the plaza in front of the U.S. Senate.
Police quickly moved in to make a number of arrests.
Republicans rebutted the attacks of Democrats, saying there was nothing in the hearings - or in the extra FBI interviews - which should disqualify the circuit court of appeals judge from joining the Supreme Court.
"Judge Kavanaugh will be an outstanding Supreme Court Justice," said Sen. Deb Fischer (R-NE).
"Don't let anybody tell you that he is obligated to a President Trump," said Sen. Charles Grassley (R-IA).
President Trump watched the final vote while on board Air Force One, as he headed to Kansas for an evening fundraising event, and a campaign rally.