Adam Forshaw, Andy Delort, Emyr Huws and William Kvist have all joined Wigan permanently on transfer deadline day.
They have paid undisclosed fees for Brentford midfielder Forshaw and French striker Delort, both 22, who joins from FC Tours in France's second division.
Huws, 20, had been on loan from Manchester City but has moved for an undisclosed fee on a four-year deal.
Midfielder Kvist, 29, has been capped 47 times by Denmark and moves on a free transfer from German club Stuttgart.
Kvist, who has signed a one-year deal, spent time on loan at Fulham last season.
Brentford accepted a bid for Forshaw last week and former Everton trainee has agreed a four-year deal with Wigan.
French forward Delort, also 22, was wanted by several Championship clubs but chose a move to the DW Stadium.
"Andy is such an exciting player. He lives to score. We have managed to bring in a proven goalscorer at the right age for under £3m and that is a testament to our club but especially to the player, his family and his agent.
"Despite huge pressure from outside during these last few days, he has never wavered in his desire to join us.
"William is a top international midfielder in the prime of his career and we are absolutely delighted to be able to sign him.
"Emyr has impressed everyone since arriving at the club and we feel that he can have a major role to play in the future of the club."
Forshaw joined Brentford in the summer of 2012 following a successful loan spell with the Bees. In total, he scored 11 goals in 100 appearances for the west London club.