The centre-back joined Barnsley from Danish side AC Horsens in 2019.

"I'm really pleased to get Mads on board. He has been on our recruitment team's list for a long time now," said Luton boss Rob Edwards.

"We watched a lot of him last season and he's performed really well and consistently for a prolonged period in English football.

"He's someone who can play anywhere across that back three for us."

Luton, who won the Championship play-off final against Coventry City to earn promotion to the top flight, did not state the length of Andersen's contract.

The 25-year-old made 175 appearances during his spell with Barnsley and becomes Luton's second signing of the summer following the arrival of Republic of Ireland winger Chiedozie Ogbene from Rotherham United.

"I'm going to play with my heart," said Andersen. "I'm going to try and give everything I can, 100% team player.

"I'll do anything for the team and, hopefully, they can use my qualities and I can help them to show their qualities."

Luton have also extended the contract of forward Cauley Woodrow, saying the 28-year-old had "committed his long-term future" to the club.