The Wales Under-21 striker, subject of an unsuccessful £175,000 bid from Crewe last month, scored a first-half brace to sink the League One promotion hopefuls and heap the pressure on under-fire Colin Calderwood.
Forest have now gone seven games away from the City Ground without a win and, after this performance in which they failed to register a shot on target, are rapidly losing ground on leaders Swansea City.
Bournemouth started brightly and nearly took the lead on 12 minutes when the electrifying Max-Alain Gradel toyed with Forest full-back Luke Chambers before sending a cross towards Vokes which Paul Smith managed to claw away with his fingertips.
Five minutes later Gradel caused more havoc in the Forest penalty area when his free-kick found Vokes whose thumping header was tipped over athletically by Smith.
It was a case of third time lucky as the same two players then linked up for Bournemouth's opener.
French winger Gradel beat Chambers, crossed to the far post and teenage striker Vokes climbed above Kelvin Wilson to head into the bottom right-hand corner.
Forest's defending failed to improve as the home side took a two-goal lead when Jo Kuffour was allowed to find space inside the centre circle and set his strike partner running free once more away from Wilson.
Vokes' first touch was not what he may have hoped for, but his strength ensured he beat his marker to the ball before smashing home his seventh goal of the season.
Chambers was enduring a torrid afternoon facing Gradel and the on-loan Leicester player turned him once more on 35 minutes before progressing towards goal but lashed his finish over.
The torment continued for Forest into the second half as the Frenchman turned inside Chambers and Wes Morgan on 50 minutes only to toe his finish narrowly wide.
Forest's best and only real opportunity arrived when Chris Cohen galloped 70 yards up the pitch and crossed menacingly towards Nathan Tyson.
Bournemouth goalkeeper Gareth Stewart was beaten by Cohen's centre, but the ubiquitous Gradel had managed to get back in time to clear the danger, in what was a thoroughly miserable afternoon for the visitors.