Billy Sharp has completed his move to Southampton from Doncaster Rovers on a three-and-a-half-year deal.
The move reunites the striker with manager Nigel Adkins who he worked under at Scunthorpe United. Sharp scored 53 times for the Iron in just 82 appearances.
He has scored 10 goals in 20 games for Doncaster this season.
Sharp told the club's official website: "I'm delighted. It has been a long time coming, but I am delighted to get it done, and now I am just looking forward to getting on the pitch and showing the fans what I can do.
"It's a massive club with huge ambitions, and that is the main reason. The gaffer and his coaching team was another reason and it felt right in my head too.
"I can't wait to get on with the challenge.
"I get on well with the fans at Doncaster and had an amazing time there and I'm gutted that I had to leave.
"That said, I am delighted that I am here and joining a really big club with a strong squad of players, hopefully I can be a cog in the team that helps get this huge club into the Premier League."
Manager Nigel Adkins added: "I'm very, very pleased. I think Bully will be a super addition to our squad, we have a superb squad here already and Billy Sharp will add to that because he scores goals.
"We give ourselves another option, and another opportunity to keep moving this football club forward.
"Billy is going to be loved here, like all our players. He is going to be wanted, valued and is going to work hard as part of the group we have here.
"It's good that I have worked with him before, but if you take that away you will see that he scores plenty of goals. He is an infectious character, who I know will be a great addition to the squad that we have."