With 72% of the estimated vote tallied, Warnock led Walker by 50.4% to 49.6%, according to Edison Research.
The race was the most expensive of the 2022 U.S. midterm election season, with more than $400 million spent.
[1/10] Reverend Raphael Warnock, Democratic Senator for Georgia, delivers remarks during a visit at a campaign office during the midterm Senate runoff elections in Norcross, Georgia, U.S., December 6, 2022.
The truth is my opponent could still win this election," Warnock told a crowd in Norcross, Georgia, on Tuesday.
This is the third Senate runoff in two years in the state - and the second for Warnock, who first won the seat in a runoff in January 2021.