Former England wicketkeeper Ambrose, 36, has agreed a new deal at Edgbaston until the end of the 2020 season.
Pace bowler Sidebottom, 30, and all-rounder Thomson, 25, have extended their stays by two years.
“It’s a welcome boost for the club to secure new deals with players of the calibre of Tim, Ryan and Alex,” said Bears sport director Paul Farbrace.
“Tim continues to be one of the leading wicketkeepers in the domestic game and will go down as a true Warwickshire great when he eventually hangs up his gloves,” he said of Ambrose, who has been with the county since 2006.
Off-spinner Thomson has been a regular in Warwickshire’s T20 Blast side in 2019, while Australia-born Sidebottom has made only one County Championship appearance this summer and was ruled out for the season with a shoulder injury in June.