West Ham moved level on points with out-of-form Wigan after deservedly beating their relegation rivals.
BoaMorte scored his first goal in West Ham colours
Luis BoaMorte latched on to an optimistic pass forward to score from 20 yards after John Filan charged from his goal but failed to reach the ball.
A sweeping second-half break was coolly finished by Yossi Benayoun, while another surging counter attack resulted in a goal for Marlon Harewood.
The Hammers are now third bottom, with Wigan above them on goal difference.
Alan Curbishley's resurgent Hammers have won five of their last seven Premiership fixtures - easily their best run of the season.
In stark contrast, Wigan have failed to win in their last seven top-flight games - and during that period have surrendered a 12-point advantage over West Ham.
With Sheffield United defeating relegated Watford, the Latics find themselves just one place above the drop zone and scrambling for their very survival.
But they can have had no complaints about the result of a fixture that started poorly, with both teams looking extremely tense.
Carlos Tevez briefly illuminated the encounter with a jinking run from the left but there had been virtually nothing of note before the Hammers took the lead after 30 minutes.
BoaMorte showed great strength to shrug off Emmerson Boyce as they raced towards Lucas Neill's long pass forward before he guided the ball past Filan, who had rashly opted to charge out of his goal.
Boyce and Tevez both chased after the ball, which bounced once and nestled in the net before either could reach it.
Buoyed after scoring, West Ham took charge, with Leighton Baines making a desperate block to deny Bobby Zamora and Tevez curling a shot narrowly wide after a jinking run from the left.
Zamora then created a shooting chance for Tevez with a deft backheel but Boyce made a crucial block to thwart the Hammers' mercurial Argentine.
Wigan's afternoon had suffered an early blow when pivotal defender Arjan de Zeeuw landed heavily on an ankle. The Latics skipper tried to carry on but was withdrawn minutes before West Ham scored.
The Latics did threaten once in the opening half - Emile Heskey heading narrowly wide from a Boyce cross - but Paul Jewell will have been glad to have reached the break for the opportunity to inspire his team.
Wigan had three strikers on the field after Jewell brought on Julius Aghahowa for Kevin Kilbane with 35 minutes left.
But a brilliant counter attacking goal from the Hammers after 57 minutes proved to be a real sucker punch.
A box-to-box move started with a defensive header that reached Benayoun via Tevez, George McCartney and Zamora.
The move had stretched the Latics and Benayoun had plenty of time to shoot across Filan, his shot going in off the post.
West Ham came close to a third when Tevez smashed a shot against the woodwork and Baines cleared off the line from Reo-Coker.
But the goal did eventually come when West Ham struck with another superb counter attack.
Tevez fed Reo-Coker, who in turn played BoaMorte clean through on goal.
The Portuguese striker, who had earlier scored his first goal for the club, unselfishly passed for substitute Marlon Harewood to slot the ball home.
Wigan manager Paul Jewell:
"West Ham were far better on the day but the manner in which we lost was disappointing.
"We are still in a better position but if we continue to play like that we won't be at the end of the season.
"It was a poor performance on such a big occasion. We have to learn from it, if not we know the consequences. The belief has to be there."
West Ham manager Alan Curbishley:
"We are still alive. To come here and win 3-0 and play the way we did was great.
"We must take it into the next game - we need to keep going. We have two more games and we need to pick up as many points as we can.
"With the run that we have been on we have given ourselves a chance."
Wigan: Filan, Boyce, De Zeeuw (Unsworth 24), Jackson, Baines, McCulloch, Landzaat (Scharner 46), Skoko, Kilbane (Aghahowa 54), Heskey, Camara.
Subs Not Used: Pollitt, Taylor.
West Ham: Green, Neill, Ferdinand, Collins, McCartney, Benayoun, Reo-Coker (Mullins 85), Noble, Boa Morte, Zamora (Harewood 68), Tevez (Spector 83).
Subs Not Used: Cole, Davenport.
Booked: McCartney, Reo-Coker.
Ref: G Poll (Hertfordshire).