Bowen completed the first hat-trick of his career after the interval before Emerson’s superb long-range blast made it four.
Yoane Wissa reduced the deficit late on, but David Moyes’ side were able to celebrate their first victory since winning at Arsenal on December 28.
Ending their longest winless streak in all competitions since 1997 was essential for Moyes, who has come under fire from frustrated fans in recent weeks.
Moyes is yet to decide whether to accept the club’s offer of a new contract, with his present deal expiring at the end of this season.
After losing their last three league games, including a 6-0 embarrassment against Arsenal, and crashing out of the FA Cup at second tier Bristol City, West Ham’s climb to eighth place was a welcome boost for the beleaguered boss.
“We needed to get three points. We played in a much more aggressive fashion tonight,” Moyes said.
“Jarrod was back to his best. He started the season really well, then got injured. If he keeps scoring he’ll be in that England squad for the Euros.”
On his future, Moyes added: “The big thing for me is to see what happens until the end of the season. I’ve enjoyed it here.”
Relegation-threatened Brentford had slipped down a place before kicking a ball on Monday after Everton’s punishment for breaching Premier League financial rules was reduced from 10 points to six after an appeal.
Brentford have now lost five of their last six league games and sit below Everton in 16th place, five points above the relegation zone.
Asked about Brentford’s perilous position in the table, boss Thomas Frank said: “I’m unbelievably irritated with our performance so that’s my only focus.
“It’s two steps back again. It’s an inconsistent season so far.”
Bowen sparkles
Bowen ended his drought in the fifth minute when Emerson’s cross reached the forward 12 yards from goal and he lashed a fierce strike past Mark Flekken at his near post.
He netted again two minutes later with a clinical first-time finish that arrowed into the far corner from Vladimir Coufal’s low cross.
Brentford were on the ropes but they punched back in the 13th minute.
Keane Lewis-Potter’s pass was perfectly weighted for Maupay, who surged into the West Ham area and stretched to lift his shot past Alphonse Areola from 10 yards.
West Ham blew a half-time lead in their 3-2 defeat at Brentford in November.
But their determination to hold the lead this time might have been heightened by an angry exchange in the tunnel between West Ham assistant coach Kevin Nolan and Maupay when the teams came out for the second half.
Bowen put West Ham in complete control in the 63rd minute.
Mohammed Kudus dinked a cross into the six-yard box, where the unmarked Bowen had found space to bury a clinical header past Flekken.
Moyes’ men got the fourth in the 69th minute when Kudus’s cross was cleared to Emerson, who lashed a brilliant strike into the top corner from 25 yards.
Wissa’s 82nd minute curler was no consolation as Brentford slumped deeper into the relegation battle.
© Agence France-Presse
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