Richardson has struggled with injuries in the last two years.
Worcestershire signing Alan Richardson says he turned down a new deal at Middlesex because the offer of first-team cricket was too good to reject.
Middlesex had offered the 34-year-old seamer a player-coach role to extend his five-year spell at Lord's.
Richardson told BBC London 94.9: "You're a long time retired and I think I've got a bit of unfinished business.
"If the body holds up, then there's no reason why I couldn't have two good years at Worcester."
The Staffordshire-born bowler, who started his first-class career with Derbyshire, has struggled with injury problems during the last two seasons at Middlesex and only took 11 wickets at 56.18 in six matches in this season's County Championship.
Richardson added: "It's been five great years - I've absolutely loved it. It wasn't a decision I made quickly or easily, but I felt it was the right move for me.
"I've got a chance to carry on playing and with the move back up to the Midlands it's a bit of a lifestyle choice as well."
Bookmark with:
What are these?