Motherwell manager Graham Alexander has welcomed their deal for Callum Slattery from Southampton.
The 22-year-old, who has agreed a three-year contract, is a product of the Premier League club's academy but has only made four appearances.
Englishman Slattery ended last season on loan to Gillingham, playing seven times for the League One side.
Alexander described him as "a young player with so much potential".
"We believe he'll add real quality to our midfield," he told his club website. "He's already played in the Premier League and we know he can be a real asset for us on the pitch.
"We've been speaking with him for a while now and it's great that we finally have him here."
Slattery, who also played five times on loan to De Graafschap in the Dutch second tier in 2020, was named on the bench for Motherwell's League Cup game against Annan Athletic on Saturday.