The Latics moved up five places to 11th in the table courtesy of goals at the start and end of the game, but the contribution of in-form Carson was just as crucial, as he made a string of saves to preserve their advantage.
There was an early scare for Wigan when Luke Chambers headed against the crossbar from a Paul Anderson corner, but the home side took the lead when Powell's corner was headed home at the back post by full-back Shotton after 12 minutes.
David McGoldrick went close to equalising in the 35th minute when he nodded an Anderson cross just wide, but for all Ipswich's pressure it was Wigan who nearly doubled their lead just before half-time when Powell's shot flashed just wide with goalkeeper Dean Gerken well beaten.
As the game progressed, Carson was the busier of the two goalkeepers - and he was forced into action early in the second half, bravely smothering the ball at the feet of Anderson.
Ipswich continued to force the pace with Carson diving low to his right to parry a Ryan Tunnicliffe shot wide.
Carson then made a brilliant save from a Christophe Berra shot from distance on 86 minutes as Ipswich continued to press.
But it was Wigan who wrapped up the win in the last minute, scoring on the counter as Powell beat a hesitant Gerken to Ben Watson's pass and tapped home from close range.
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