Arsenal's miserable run continued as goals from Callum Wilson and Jordon Ibe saw Bournemouth come from behind to put a further dent in the Gunners' pursuit of a top-four place.
Arsene Wenger's men are now without a win in five games in all competitions, and five points adrift of fourth place in the Premier League.
Defender Hector Bellerin had given the visitors - playing without forward Alexis Sanchez - the lead when he latched on to a defence-splitting Alex Iwobi pass to squeeze the ball past Asmir Begovic.
But Wilson took advantage of Petr Cech's indecision as he got to Ryan Fraser's low cross before the Arsenal keeper and poked it past him.
The 25-year-old then turned provider, bringing down Lewis Cook's cross for Ibe to rifle home, says BBC.
Eddie Howe's side savoured a first ever Premier League victory over Arsenal, at the seventh attempt, the victory moving them up to 13th place and four points away from danger.
But for Wenger, who was completing his three-game touchline ban for verbally abusing an official, it was further disappointment as speculation mounts that Sanchez's departure is imminent.
A strong first-half Gunners performance, in which 20-year-old Ainsley Maitland-Niles rattled the crossbar, was undone in less than five calamitous second-half minutes.