A Vitaly Janelt own goal off his arm from a Milos Kerkez cross gave the hosts the lead after 17 minutes, but Brentford drew themselves level through Yoane Wissa on the half an hour mark.
Christian Norgaard was the fastest to react to a bouncing ball in the Bournemouth box to smash in the visitors’ second with just under 20 minutes to play.
The hosts were unable to find a late equaliser and were beaten at Dean Court.
Andoni Iraola made one change from his side that brought a point back to the south coast from Spurs last weekend, with Illia Zabarnyi returning from suspension in place of James Hill, who dropped to the bench.
Thomas Frank named an unchanged team from that which lost against Aston Villa last weekend.
The Cherries had an early shot on goal as Milos Kerkez was set by Justin Kluivert, but the Hungarian couldn’t get too much power on the shot and it was straight at Bees keeper Mark Flekken.
It was a good opening 15 minutes for the hosts without any clear-cut chances, although the visitors had some good spells of possession in the Bournemouth half, without and openings themselves.
And the Cherries’ good start was rewarded after 17 minutes.
Kerkez’s brilliant run in behind the defence was found by a good pass from Antoine Semenyo, the Hungarian’s cross finding the back of the net via Janelt’s arm.
The visitors were back on level terms on the 30-minute mark, though, Wissa heading home from a Brian Mbeumo corner, the DR Congo international getting to the set piece before Kepa who came to punch.
Mbeumo went close himself moments after the equaliser, his shot deflected wide.
Evanilson saw a shot tipped onto the bar by Flekken, the Brazilian meeting Dean Huijsen’s cross but his effort went into the ground and the keeper tipped onto the bar and Brentford cleared.
Janelt shot over the bar after he was teed up by Kristoffer Ajer, before Evanilson and then Ryan Christie shot wide, the sides going into the interval level at 1-1.
The Cherries made a quick start to the second half, Semenyo rattling the crossbar early on with a header from a Kluivert cross after he drifted between the centre backs.
Brentford saw out the early pressure at the start of the second period, Mbeumo seeing a shot caught easily by Kepa after a deflection off Kerkez after 57 minutes.
Shortly after the hour mark, the Cherries broke well at speed, Evanilson flying down the left, the Brazilian’s cut back across the six-yard box caught by Flekken with Semenyo behind him waiting to tap in.
Marcus Tavernier curled a shot just wide of the top corner, before Christie was replaced by Luis Sinisterra in the first change of the evening.
The Bees took the lead after 71 minutes, the Cherries defence allowing the ball to bounce in the box from a Kevin Schade long throw, and Norgaard was the fastest to react to smash the ball into the back of the net.
There were loud shouts for a Bournemouth penalty as Evanilson went down in the box, but the Brazilian was marginally offside.
David Brooks and Hill came on for Kluivert and Tyler Adams, with the Welshman went close to an equaliser, shooting straight at Flekken from a Sinisterra cross.
Sinisterra was then himself replaced by Dango Ouattara and Daniel Jebbison came on for Zabarnyi as Bournemouth sought a late equaliser.
Semenyo drew a comfortable save out of Flekken as the game entered five added minutes, the Cherries unable to find a late equaliser and falling to a disappointing defeat.
**AFC Bournemouth:** 13, Kepa; 4, L. Cook (c); 27, I. Zabarnyi (D. Jebbison 85’); 2, D. Huijsen; 3, M. Kerkez; 10, R. Christie (L. Sinisterra 67’ (D. Ouattara 85’)); 12, T. Adams (J. Hill 79’ (booked, 89’)); 16, M. Tavernier (booked, 68’); 19, J. Kluivert (D. Brooks 79’); 24, A. Semenyo (booked, 75’); 9, Evanilson.
**Brentford:** 1, M. Flekken; 20, K. Ajer (S. van den Berg 72’); 22, N. Collins; 5, E. Pinnock; 23, K. Lewis-Potter; 6, C. Norgaard (c); 27, V. Janelt (Y. Yarmoliuk 72’); 19, B. Mbeumo; 24, M. Damsgaard (B. Mee 85’); 7, K. Schade (Y. Konak 85’); 11, Y. Wissa.