Fulham are paying £20m up front with a further £5m due in bonuses. Berge has penned a five-year contract.
Speaking to FFCtv, Berge said: “It feels fantastic. It’s been a little bit back and forth the last few weeks, but I’m finally sitting here in the shirt in this beautiful stadium, knowing that my future is here, which feels great.
“Fulham has always been a team that excited me. I’ve played them both in the Championship and Premier League, and it’s fantastic how they play, 4-3-3, 4-2-3-1.
“The DNA of the Club is to be dominant, aggressive, front-footed, and play nice football, and I think that suits me.”
Cottagers chief Tony Khan added: “I'm excited to welcome Sander Berge to Fulham! Sander has tremendous experience playing in the Premier League and in international competition, and we believe that he'll be a great addition to our squad, as we look forward to our first home game of the season this weekend!"