Goals from Shaleum Logan and Gary Alexander ensured Uwe Rosler's reign as Brentford boss started with a victory.
Yeovil fell behind when Alexander converted from the penalty spot after Nathan Jones had handled in the area.
Logan, a summer signing from Manchester City, doubled Brentford's advantage when he fired home from 12 yards following good work from Sam Saunders.
The Glovers' best chance fell to Gavin Williams but his 30-yard effort was tipped wide by keeper Richard Lee.
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Brentford manager Uwe Rosler told BBC London 94.9:
"I thought it was important to take the momentum from pre-season into the league.
"The lads did remarkably well especially in the first half, I felt we had a very good balancing between playing the way we want to play but also showing some toughness and directness.
"We put them under pressure from the first minute."
Yeovil Town manager Terry Skiverton told BBC Somerset:
"I think everyone in this stadium today got caught up in the Uwe Rosler show. I think we did as a team, we didn't come out and play.
"How was that meant to be a penalty? I just couldn't fathom it - I'll be asking for some feedback on that.
"Taking that first goal that was gifted to them away from the game...we seem to have given a result away."
Brentford 01 Lee 03 Woodman 05 Eger 14 Logan 22 Osborne 08 Douglas 11 Weston (Saunders - 59' ) 18 McGinn (MacDonald - 72' ) 40 Reeves (O'Connor - 81' ) 09 Donaldson 29 Alexander Substitutes 31 Moore 06 Balkestein 02 O'Connor 07 Saunders 10 MacDonald Yeovil Town 01 Steer 02 Ayling Booked 03 Jones 04 Ngala 05 Huntington 14 Ehmer (Haynes-Brown - 56' ) 08 Upson Booked 10 Williams 20 Wotton Booked 09 MacLean Booked (Fallon - 56' ) 29 Obika (A Williams - 62' ) Substitutes 19 Haynes-Brown 11 Edgar 07 A Williams 18 Agard 37 Fallon