The prolific pair took their combined tally for the season to 33 goals. In between two clinical strikes from Roberts, Ellington sandwiched a crucial penalty, which ultimately killed off Crewe's spirited revival at the Alexandra Stadium.
Roberts fired the Latics in front after just two minutes and 20 seconds when Gary Teale's lofted cross was knocked back by Lee McCulloch for him to connect with at the far post.
Jimmy Bullard came close to making it two soon after when he moved into space and drilled an effort inches past Clayton Ince's far post.
Yet while they struggled to get out of their own half early on, Crewe almost made the most of a couple of chinks of daylight they were glimpsed around John Filan's box.
Andy White latched on to Ian Breckin's loose clearance and hooked a volley a yard or two wide, while Anthony Tonkin's low shot at the end of a surging run deceived Filan, who was glad to scramble it around his far post.
But Ellington hit the side netting with a fierce drive and it was something of a surprise when Chris McCready's cross from the right resulted in a Crewe equaliser a minute before the interval.
Midfielder Lee Bell stole in to plant a free header at Filan and when the keeper spilled the ball White reacted quickly to smash in an opportunist close-range effort.
Crewe came out at the start of the second period with their tails up and Mark Rivers almost broke free twice.
The home faithful were roaring in the 57th minute, but the flag had been raised against Rivers as he took David Vaughan's pass and fired into the bottom corner.
Wigan's play didn't look nearly so assured as in the first 45, but nevertheless Ellington came close to stretching a boot on to partner Roberts' cross from the right.
And Wigan's leading marksman was handed the opportunity to restore his side's lead when Tonkin failed to keep pace with Teale's surging run down the right of the home box.
There was little doubt the left-back caught the midfielder with an outstretched boot and Ellington's cocky 67th-minute penalty saw Ince go to his left as the ball was rolled home down the other side.
Crewe's hopes of another revival ended when with 15 minutes left. Ellington found his partner through the middle with a careful pass and Roberts took the ball on, brushing aside Colin Murdock, and placing a low shot into the bottom corner from just inside the box.