Defender Ryan Sweeney has signed for Stags on a free transfer from Stoke City.
The 21-year-old centre-back has signed a two-and-a-half year deal with club after spending this season on loan at One Call Stadium from the Potters.
Sweeney has made 31 appearances for Mansfield this term, and is a key member of the back-line with the best defensive record in Sky Bet League Two.