The game’s first chance went to Brentford around the 10th minute.
Said Benrahma struck a swerving effort towards goal from the edge of the area and Forest keeper Costel Pantilimon did just enough to parry the ball away.
With their first chance of the game, Forest took the lead inside the 16th minute.
Lewis Grabban, restored to the side after starting the last two games on the bench, showed his quality by getting in behind the Brentford back line and slotting in at the second time of asking after Daniel Bentley was equal to his initial effort.
Brentford were looking for an instant response and Yoann Barbet almost produced it with a long-range free kick but Pantilimon got across well to palm the ball away for a corner.
In the 25th minute, Forest almost got what would have been a crucial second.
Matty Cash’s long throw from the right found Joe Lolley running into the box but he failed to make proper contact on it and Bentley saved.
It was an end-to-end encounter and the Bees almost stung Forest.
Neal Maupay appeared to be through on goal but delayed pulling the trigger and, under pressure from Jack Robinson, ultimately wasted the opportunity.
At the other end, Lolley got free of his man on the left flank and charged forward before pulling the ball back for Leo Bonatini who failed to direct his first-time shot towards goal.
With two minutes to go in the first half, Brentford went agonisingly close to drawing level.
A raking ball over the top found Moses Odubajo marauding forward and he dinked the ball over the advancing Pantilimon but the ball was hacked off the line.
Forest introduced Diogo Goncalves at the break in place of Leo Bonatini and he almost doubled Forest’s lead in the 51st minute.
A beautiful through ball put Goncalves clear and he skipped round Bentley before seeing his shot cleared off the line by Dalsgaard.
With an hour gone, Brentford struck the post with Forest breathing a big sigh of relief.
Romaine Sawyers had Pantilimon beaten but his powerful effort cannoned back off the left-hand post and Forest cleared the danger.
In the 65th minute, Forest were presented with a golden opportunity to take control of the game after being award a penalty.
Grabban was the man brought down and he stepped up to take it but Bentley brilliantly denied the former Bournemouth man before getting back to his feet to deny Ben Watson on the rebound.
Time was running out for Brentford and they continued to put Forest under pressure in their search for an equaliser. Sergi Canos and Ollie Watkins both had shots blocked on their way through to goal before Maupay saw a near-post effort deflect just wide.
Any hopes the Bees had of getting something from the game were severely dented as Forest added a second. Bentley failed to deal with Joe Lolley’s in-swinging corner and the ball landed on the head of Molla Wague who, only minutes after coming on for his Forest debut, headed in his first goal for the Reds.
Brentford finally got their goal in the 89th minute to set up a tense end to the game.
Sergi Canos halved the deficit with a terrific, stabbed effort which caught Pantilimon off guard and nestled into the bottom corner.
However, it proved to be just a consolation as Forest hung on for a big three points.
FOREST (4-2-3-1): Pantilimon (GK); Janko, Milosevic, Robinson, Osborn; Watson, Yates; Cash (Wague 71), Bonatini (Goncalves 46), Lolley; Grabban (Ansarifard 87). SUBS NOT USED: Steele (GK), Murphy, Carvalho, Yacob
BRENTFORD: Bentley (GK), Odubajo, Maupay, Watkins, Mokotjo (McEachran 71’), Sawyers, Benrahma (Canos 63’), Dalsgaard, Jeanvier, Konsa, Barbet. SUBS NOT USED: Daniels (GK), DaSilva, Ogbene, Forss, Bech Sorensen
REFEREE: Robert Jones.
ATTENDANCE: 27,829 (1,182 away).
FOREST MAN OF THE MATCH: Ryan Yates.