Although the transfer figure has been quoted as undisclosed, it is believed to be in the region of £6.5 million, although unconfirmed. Emile Heskey at £5.5million and Charles N'Zogbia at £6.0m plus Ryan Taylor are the previous record transfers.
Boselli has joined from Estudiantes and was part owned by Boca Juniors. The transfer saga has been long running and officials at the club are delighted to have his signature.
It is hoped that Boselli will fire the goals for the Latics as manager Roberto Martinez hopes to make a real impact on the Premier league next season.
Speaking about the capture of Boselli, Martinez told the club's official website: "Mauro is a goalscorer, who lives to put the ball in the back of the net and he is somebody we have been looking at for a long time.
"At 25-years old he is at a perfect moment in his career to come and play in the Premier League, and he has all the right qualities to make his mark at this level. He is a clever player, a natural finisher who can cause havoc in the penalty area, and he gives the team some great new options with the variety of roles he can play.
"We want him to reach his full potential here and bring plenty of smiles to the Latics fans. These deals with clubs on the other side of the world are very difficult to complete and it has taken many hours of to-ing and fro-ing until everything was settled.
"I would like to play tribute to Chief Executive Brenda Spencer who has worked tirelessly to get this deal through."
Should the club manage to hang on to Charles N'Zogbia and Hugo Rodallega then the club will have a particularly dangerous strike force next season.
