Hull City have triggered an option to turn Ryan Giles' loan deal into a permanent move to the MKM Stadium.
The left-back joined the Tigers in January and made 17 Championship appearances as they finished one place outside the play-off places.
Giles, who made 11 Premier League appearances for the Hatters in the first half of last season, also has extensive Championship experience from loan spells at Coventry City, Rotherham United, Cardiff City, Blackburn Rovers and Middlesbrough.
The 24-year-old has signed a three-year contract with the option of an extra year.