Forren moved to Southampton from reigning Norwegian champions Molde after initially being linked with a move to Liverpool.
But now he has moved to the south coast Forren wants to push on with the Saints after being sold on the Barclays Premier League by Molde boss Solskjaer.
"It has always been a dream to play in the Premier League," he said. "After a chat with Nicola (Cortese, Southampton chairman) there was no doubt for me with the plans he has for this club in the future.
"To be a part of that was hard to say no to, it is a team that is on its way up and a team who wants to play football - I was sure this was the right club for me. The club really wanted me and this feels the right club to play football in.
"For me he (Solskjaer) has meant everything to me, he is a great coach and I have taken big steps because of him. I spoke a lot to him about the move and he really wanted to give me this opportunity so I have to thank him for that."
Forren could make his debut for Southampton when they travel to league leaders United and former Old Trafford favourite Solskjaer should anticipate a call from his former centre-back.
"Maybe I will give him a call," he said.