Albion went 1-0 ahead in the 34th minute courtesy of a sublime volley from Trossard. Enock Mwepu delivered a long ball over the top from the halfway line and Trossard sent a first-time finish over advancing Bees goalkeeper Alvaro Fernandez for his fourth of the season.
Brighton doubled their advantage to 2-0 three minutes before the break as Neal Maupay scored against his old club.
The French forward collected the ball from Jakub Moder before unleashing a stunning effort into the top right corner from the edge of the box.
Trossard however did not appear for the second half and was replaced by striker Danny Welbeck, who made his first appearance since September following hamstring surgery.
Albion head coach Graham Potter admitted Trossard has been struggling this week and is also doubtful for Wednesday trip to Chelsea.
"It was precautionary with Leo," said Potter when asked why he came-off at halftime.
"He has had a tightness in his hamstring and has not been feeling the best this week. We will see and it will all depend on the recovery. We will add it all up, see how he goes and see what the next 24 hours bring.
"We will have to make a last minute decision but that is how it has been pretty much every week."
Potter was delighted to welcome Welbeck back but admitted the former Man United striker played for longer than he planned on his first outing since September.
There was also a return for midfielder Steven Alzate who came on in the final stages and help Brighton to the 2-0 win.
"We were planning not to play Danny for so long but in the end he managed the 45. It was great to have him back on the pitch and with Steven [Alzate].
"It is nice we can get those guys back because we were affected a lot against Wolves."