Gosling struck an 84th-minute winner when he flicked the ball over Kepa Arrizabalaga and into the net despite standing with his back to goal, ending Bournemouth’s run of five successive league losses.
Kepa was made to pay for another bout of poor positioning, while Chelsea were punished for an incoherent and toothless display that will have left boss Frank Lampard far from impressed.
Lampard has demanded more “personality” from his Chelsea players in a bid to arrest their league slump, but despite a host of big names there was precious little star quality on view in west London.
Instead, in-form striker Tammy Abraham was too isolated too often, with team-mates unable to provide the service to capitalise on his sharpness in front of goal.
Eddie Howe’s Bournemouth headed into the clash missing eight injured senior players and fretting about the source of their next league victory.
The Cherries had not won since seeing off Manchester United 1-0 at home on November 2, and would have expected a stern test in the capital.
Howe’s men kept their heads and shape throughout however, even rebuffing a late Chelsea rally after Lampard threw on Michy Batshuayi as a second striker.
While Bournemouth were left to toast a vital win, Chelsea could only lament another below-par league performance.
After Tuesday’s high of seeing off Lille 2-1 to reach the Champions League’s last 16, this was a serious bump down to earth for Lampard and the Blues.
Ryan Fraser saw a low shot blocked in a rare Bournemouth raid, but otherwise it was 45 minutes of bluster.
Chelsea rode their luck on a host of occasions after the break as an emboldened Bournemouth started to chase the game.
Kurt Zouma pulled off a fine last-ditch sliding tackle to deny Josh King, with an out-of-position Kepa furiously backpedalling.
Jefferson Lerma was hugely fortunate to escape without conceding a penalty for elbowing away Willian’s free-kick as Chelsea rallied as the match ticked past the hour.
Callum Hudson-Odoi added impetus off the bench, and his cross eventually led to Emerson Palmieri heading straight at Ramsdale.
From point-blank range the Chelsea left-back should have easily nodded home.
But instead the Blues were left to battle away as the turgidity continued.
Lampard went for broke by sending on Batshuayi, sacrificing Jorginho in chasing a much-needed win.
And yet it was Bournemouth prevailed, as Gosling conjured an improbably lob to stun Kepa, with Azpilicueta unable to clear off the line.
The goal was rightly awarded after a Video Assistant Referee (VAR) check, with the ball clearly crossing the line despite Azpilcueta’s best efforts – and Philip Billing not active as he was retreating when the ball was played in to Gosling.