The former West Ham midfielder replaced Marc Pugh in the 66th minute and tapped in a delightful Ryan Fraser cross just six minutes later.
And it proved to be the difference as the Cherries earned all three points and recorded their third clean sheet in succession.
Bournemouth scored after 26 seconds in their opening game victory at Huddersfield and they almost started in a similar manner here, with influential midfielder Matt Ritchie trying his luck from all of 25 yards - but David Button was able to watch it sail safely over in the Brentford goal.
The frenetic pace continued at both ends with Andre Gray smashing the underside of Lee Camp's bar after six minutes following a neatly-worked set-piece involving Jake Bidwell.
Just a minute later the away side were again threatening to take full advantage of a free-kick as the Cherries were yet again punished for taking down Moses Odubajo.
Another neatly worked set-piece from the away side saw Odubajo force Camp into a smart save, with the former Derby stopper getting down well.
Bournemouth almost punished the away side for not taking their flurry of chances via French striker Yann Kermorgant - but the number 18 saw his curling right-footed effort tipped round the post.
The second half at the Goldsands Stadium started much like the first with Bournemouth in the ascendency within minutes of the restart.
Eddie Howe's club should have taken the lead through striker Callum Wilson, who found himself unmarked inside the box but was unable to get a clean strike on the ball with the wind playing its part - and the impressive Bidwell was able to clear the ball safely off the line.
The blustery conditions almost handed Brentford an unlikely lead with just over an hour on the clock as Tottenham loanee Alex Pritchard's long range free-kick was punched away by Camp.
Realising that Brentford were gaining the momentum manager Howe rung the changes, giving a home debut to Stanislas.
And the manager's faith in his replacements was rewarded just six minutes left as the former West Ham midfielder tapped home fellow sub Fraser's dangerous cross.
Pritchard was at it again with moments on the clock as he forced Camp into yet another smart save but it just was not to be for the away side.
In fact it could have got a whole lot worse in injury time as Stanislas yet again threatened the away side's defence but a smart block from Craig denied the summer signing his second.