With certification, Murkowski becomes the first U.S. Senate candidate since Strom Thurmond in 1954 to win a write-in campaign.
The official margin of victory over her nearest opponent, Republican rival Joe Miller, was more than 10,000 votes. Miller, a Sarah Palin-backed tea party favorite, defeated Murkowski in the August primary.
Miller was expected to announce Friday whether he'll continue his legal challenge to the state's handling of the election and its counting of write-in votes for Murkowski.
Miller argued that the state should have strictly adhered to a law calling for write-in ballots to have the ovals filled and either the candidate's last name or name as it appears on the declaration of candidacy written.
The state allowed for ballots with misspellings to be counted toward Murkowski's total, with the director of the state Division of Elections, in consultation with state attorneys, using discretion to determine voter intent.
Last week, the state Supreme Court, in a 4-0 opinion, called voter intent "paramount" and upheld a lower court decision that refused to overturn election results favoring Murkowski.
The Associated Press contributed to this report