- Kavanaugh was tapped in July to become Trump's second pick for the nine-member high court in just two years.
- The vote follows a politically fraught confirmation process in which Republicans and Democrats grappled over Kavanaugh's views on controversial legal rulings and the disclosure of hundreds of thousands of pages of documents related to the nominee.
- Kavanaugh was also accused of sexual misconduct by multiple women. He denied the allegations, and the Senate extended the confirmation process to allow for further consideration of his nomination.
Brett Kavanaugh was sworn in on Saturday as the 114th Associate Justice of the Supreme Court, after the Senate voted largely along party lines to confirm his nomination amid an emotional, weeks-long debate characterized by explosive allegations of sexual assault.
With one senator voting present, Kavanaugh officially ascended to the nation's highest court, and in doing so solidified a conservative-leaning bloc of justices that will deliberate on some the country's most polarizing legal questions. His confirmation followed an unusually partisan process that united Republicans, but divided the population in an era defined by the public's reckoning with sexual misconduct.
Kavanaugh, 53, a federal appeals court judge who investigated President Bill Clinton and worked for his successor, President George W. Bush, is President Donald Trump's second high court nominee in two years, following Justice Neil Gorsuch, who was confirmed in 2017.
Kavanaugh's confirmation became all but assured on Friday, after a wavering group of senators made their preferences public in the wake of a supplemental Federal Bureau of Investigations probe. The week-long investigation revealed nothing new in the allegations against Kavanaugh, but was met with furious criticism by many Democrats.
After the narrow vote, Trump phoned Kavanaugh in a congratulatory call, and signed his commission on Air Force One, the White House said.
"The White House applauds the Senate for confirming President Trump's nominee Judge Brett Kavanaugh to the Supreme Court. Later today, the president will sign his commission of appointment and he will be officially sworn in," said Raj Shah, a White House spokesman.
A celebratory event will reportedly be held for Kavanaugh in the White House's East Room on Monday night.
Republicans and Democrats grappled for weeks over Kavanaugh's views on controversial legal rulings and the disclosure of hundreds of thousands of pages of documents related to the nominee. But in September, the judge's seemingly clear path toward a winning vote in the GOP-controlled Senate became obstructed by an accusation of sexual assault that allegedly occurred decades ago, which mushroomed into multiple allegations that sparked weeks of agonizing debate.
California professor Christine Blasey Ford sent a letter to California Democrat Rep. Anna Eshoo alleging that, in the 1980s, an intoxicated Kavanaugh and his classmate, Mark Judge, had pinned her down on a bed, covered her mouth and attempted to take her clothes off. Ford, Kavanaugh and Judge were all in high school at the time.
For his part, Kavanaugh vehemently denied the allegations, which culminated in an emotionally pitched testimony on the same day Ford appeared before the Senate Judiciary Committee to discuss the incident in question.
The soft-spoken accuser was widely viewed as credible and sympathetic, while the judge's fiery, combative performance inspired conservatives, including the president, to ramp up their support for him.
Beforehand, Democrats' chances of successfully stopping Kavanaugh's confirmation were broadly viewed as slim throughout the majority of the confirmation process. Kavanaugh's record and character were extolled by conservative judicial groups, as well as some prominent figures on the left, including self-described "liberal feminist lawyer" Lisa Blatt.
Senate Majority Leader Mitch McConnell had set in motion the process to quickly confirm Kavanaugh after the hearing, but retiring Sen. Jeff Flake, R-Ariz., pushed for a week-long delay so the FBI could re-open its background investigation into the judge to specifically look into the allegations against him. The brief probe, which was limited in scope, wrapped up before the one-week deadline.
Tensions between Republicans desperate to confirm Kavanaugh before the November midterm elections, and Democrats determined to slow down the process, boiled over in Senate Judiciary Committee hearings earlier in September.
Democrats grilled Kavanaugh on topics including the constitutionality of abortion, the possibility of indicting a sitting president and the limits of a president's pardon power. Kavanaugh, often citing the precedent set by prior nominees' judicial hearings, generally declined to discuss his views.
The two parties appeared mostly unified in support or opposition of Kavanaugh. But with Republicans holding a razor-thin majority in the Senate, a handful of politically moderate or electorally vulnerable senators on either side of the aisle quickly gained the most attention.
Among them was Collins, a moderate Republican who had spoken positively of Kavanaugh and said he had told her that he considered the consequential 1973 Roe v. Wade case, which legalized abortion, as "settled law."
Three red-state Democratic senators — North Dakota's Heidi Heitkamp, Joe Donnelly of Indiana and Manchin — who voted for Gorsuch in 2017 had also come under intense scrutiny from journalists and advocacy groups. Heitkamp and Donnelly announced their opposition to Kavanaugh. On the other hand, Manchin announced his support for the nominee quickly after Collins made her announcement.
--CNBC's Javier E. David contributed to this article.