Rushworth, 36, negotiated his release having cited a desire to relocate for personal reasons and has since penned a two-year deal at Edgbaston with an option for a third.
He joins with a hard-won reputation as one of the most reliable seam bowlers in the country, with a first-class tally of 603 scalps and an average of 22.61. Warwickshire won the LV= Insurance County Championship in 2021 but saw their form drop off this summer, narrowly avoiding relegation from the top flight.
Rushworth's signing represents a move to bolster their bowling stocks with a player of proven pedigree.
"I'm delighted Rushy has chosen us to join us," said first-team coach Mark Robinson. "He's keen to make a fresh start, hungry to succeed and will give us some real quality and obvious experience which at times we lacked last year.
"With the injuries we had last season our depth of bowling couldn't cope, so it's important we are able to add some more quality and deepen our resources.
"He's a wicket taker, make no mistake. He has 603 first class wickets to his name and he has told me he wants to come because he wants to win another County Championship before he retires, which is exactly the language you want to hear.
"We're really looking forward to welcoming him to Edgbaston."