Matt Sherratt is to rejoin Worcester from Ospreys to succeed Neil Doak as backs coach for the 2020-21 season.
Sherratt, 43, began his coaching career with Warriors, spending five years in the Academy at Sixways.
He then worked for Bristol and Cardiff Blues, and also as number two to Rob Howley on Wales' 2017 summer tour to Samoa and Tonga before joining Ospreys.
Doak is due to leave Sixways "by mutual agreement" when his contract at Worcester ends next summer.
"Matt is an outstanding coach with an excellent reputation and has strong links with the club, having begun his coaching career here," said Warriors director of rugby Alan Solomons.
"I know he is highly thought of by the Welsh international players. In addition, he is friends with our academy manager Mike Hall and our incoming forwards coach Jonathan Thomas, which augurs well for the synergy of our staff. Over and above all that he is a terrific bloke."
Ospreys managing director Andrew Millward said: "We are all disappointed with his decision to leave at the end of the season but understand his desire to be closer to his young family."
Worcester currently lie fourth in the Premiership, while Ospreys are one off the bottom of the seven-team Conference A in the Pro14.