Brighton said the veteran has signed a one-year deal with the south-coast club after a trophy-laden spell with Liverpool where he won the Champions League, the Premier League, the FA Cup and League Cup in 332 appearances for the club.
Brighton will be playing in Europe for the first time after they finished sixth to qualify for the Europa League and the club's technical director David Weir said the Milner's big stage knowledge would come in handy.
"We are delighted that James has agreed to join us after a hugely successful period at Liverpool. His experience speaks for itself with the amount of games he has played and the trophies he has won throughout a decorated career," Weir said.
"These games include European competition, which will be of huge value to us as we embark on our first season in Europe."
Milner is one of the ever-present players in England's top flight having made his debut with Leeds United in 2002 as a 16-year-old.
With 619 Premier League appearances, he is third on the all-time appearances list behind Gareth Barry (652) and Ryan Giggs (632).
