Wickman was obtained from Cleveland July 20.
Entering Wednesday night's game against Washington, he had converted 19 of 20 save opportunities for Atlanta. His lone blown save as a Brave came July 23 at Philadelphia.
No financial details were mentioned.
"Bob's impact on our bullpen and team has been obvious," said General Manager John Schuerholz in a statement on the team's Web site. "He is a proven closer and we look forward to beginning the 2007 season with him on our club."
In his career, the 37-year-old Wickman -- who also has pitched for the New York Yankees and Milwaukee Brewers -- has a 60-56 record, 244 saves and a 3.58 ERA in 774 appearances.
He is a two-time all-star and is tied with Hall of Famer Don Sutton for 41st place all-time in games pitched.