Albion celebrated their centenary with a 12th successive home League win to stay on top of the table.
Captain Eddie Howe turned from hero to villain for Bournemouth in a competitive South Coast derby.
He headed the visitors level in the second half after Paul Watson had scored his third goal in as many Second Division games at Withdean for the Seagulls early on.
Howe then put through his own net within four minutes of equalising to present Albion with their fourth League win in a row.
Bournemouth had been hammered 6-0 at Peterborough on Tuesday and Albion threatened to run riot against them again before another sell-out crowd of 6,714.
Bobby Zamora had a header brilliantly saved by Gareth Stewart and Richard Carpenter chipped against the crossbar before Watson gave Albion a bizarre 13th minute lead.
His inswinging cross from the right wing found the far corner of the net, although Lee Steele tried to claim a touch.
Albion played some flowing football in the opening 45 minutes, but Bournemouth always looked capable of nicking a goal.
Michel Kuipers saved shots in both halves by Carl Fletcher to keep Albion's lead intact.
The unmarked Howe headed Bournemouth back on terms on 76 minutes from a James Ford free-kick, much to the annoyance of Albion boss Micky Adams, who hates letting goals in from set pieces.
Howe cheered him up four minutes later, knocking the ball into his own net from close range via a post after Danny Cullip back headed a long throw by substitute Kerry Mayo.
The Seagulls have been drawn away to Swansea, one of Adams' former clubs, in the LDV Vans Trophy on October 16.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article