The team later confirmed the extension. Terms of the deal were not disclosed, but Jackson said at a news conference it was for two years. He had one year remaining on his contract.
"I always said I wanted to be here, and now I have that opportunity to be here," said Jackson. "I'm glad this is over with and we can focus on playing football. We're doing some tremendous things here and I think we can get a lot accomplished in three years."
General manager Buddy Nix said extending Jackson was a matter of retaining "one of the best backs" in the NFL.
"We've always said we're going to keep our good players and we've done it again today," Nix said.
The five-year veteran played in 10 games last year, rushing for 934 yards and six touchdowns. His season was cut short due to a fractured fibula suffered against the Miami Dolphins in Week 11.
Jackson told the media he was 100 percent healed and in shape but not quite in "football shape."