The 39-year old was initially due to be offered an 18 month extension at Derby ahead of the expiry of his contract next week, but with the EFL putting them under a transfer embargo he was unable to re-sign.
The veteran centre-back is now signing for Stoke, who added Taylor Harwood Bellis on loan from Manchester City this week and are trying to sign Chelsea midfielder Lewis Baker.
Phil Jagielka is set to sign for Stoke City as a free agent after leaving Derby County this month
Wayne Rooney is furious after not being able to re-sign Jagielka due to their transfer ban
A Derby statement said: ‘Derby County would like to place on record its sincere thanks to Phil for his commitment and efforts both on and off the pitch whilst with the club and wish him every success in his future endeavours.’
Jagielka joined Derby as a free agent in August on a short-term deal. He has started 20 of their 25 league games and formed a first-choice centre-back pairing with Curtis Davies.
Sportsmail understands that Rams boss Wayne Rooney, who played with Jagielka for Everton and England, is furious that his former team-mate has been made to leave the club.
Rooney was desperate to keep his former England and Everton team-mate at Pride Park
But Jagielka was unable to re-sign due to their transfer ban and is now set to head to Stoke