Maynard spent the second half of last season on loan at the DW Stadium as he tried to rebuild his career following a cruciate knee injury.
But he showed little sympathy for the Latics who have now taken only one point from their first three league games.
Latics boss Uwe Rosler had masterminded a memorable FA Cup victory at the Cardiff City Stadium back in February but this time he was stunned by a familiar face, Maynard sliding home his first goal of the season from close range after 53 minutes.
Cardiff handed a debut to former Reading centre-half Sean Morrison with club captain Mark Hudson dropping out, but kept fellow new signing Anthony Pilkington on the bench after his move from Norwich.
Wigan had Cardiff old boys Don Cowie and Andrew Taylor in their ranks but the Latics were almost caught cold inside two minutes when poor defending allowed Aron Gunnarsson to shoot on the turn.
Scott Carson blocked that effort but the former England goalkeeper was a relieved man following his poor clearance after 21 minutes.
Carson's kick flew straight to Maynard on the edge of the penalty area but the striker dawdled before being barged over by the retreating Cowie.
Maynard wanted a penalty but referee Robert Madley felt it was a fair shoulder to shoulder challenge.
Wigan's attacking threat had been sporadic at best but after 28 minutes Taylor crossed from the left and Callum McManaman forced skipper-for-the-night David Marshall into a smart tip over.
Bluebirds boss Ole Gunnar Solskjaer abandoned his diamond formation after half-an-hour and reverted to a conventional 4-4-2 with Peter Whittingham more comfortable in a central role.
Gunnarsson was not so at home on the right but on the stroke of half-time he laid the ball back into the path of Tom Adeyemi who tested Carson from 25 yards.
Pilkington's arrival at half-time for Mats Daehli pepped up Cardiff and growing pressure was rewarded with a deserved lead.
Fabio swung over a cross from the left, Morrison headed it down and Kenwyne Jones touched it into Maynard's path for the easiest of finishes.
Wigan responded when Cowie broke down the right and crossed for the unmarked Marc-Antoine Fortune but the striker's touch was heavy and Marshall was able to intervene.
Rosler sent on substitutes Oriol Riera and Martyn Waghorn to add fresh attacking energy and the move almost paid off 20 minutes from time.
Cowie was again the instigator and his cut-back found Waghorn who placed his shot wide and Cardiff held firm after that.