The midfielder underwent shoulder surgery on Monday and is likely to be out of action for the next 12 weeks.
The former Leicester and Peterborough player, who has dislocated his shoulder against Hartlepool and Exeter this season, was hoping to delay surgery until the end of the season, but it was deemed not possible.
Wesolowski has started 26 games this season, scoring four goals.
Jamse Tarkowski has credited Sean Dyche for his England call-up, admitting he would have found it 'difficult' to represent Poland.
Jordan Hugill says he is desperate to prove he is ready to play a bigger part in West Ham's battle against relegation.
Harry Maguire says he's discovered his best form at Leicester this season as he seeks to cement his spot in England's World Cup squad.