Veteran Andy Morrell scored Blackpool's second-half winner to send Oldham crashing to a fourth straight defeat.
The 32-year-old struck in the 67th minute with a simple tap-in from strike-partner Ben Burgess's cross.
Home Paul Rachubka had to be at his best to tip Paul Warne's 20-yard effort onto the bar, before Chris Porter hit the woodwork again with a free-kick.
However, Blackpool's win was deserved and Keigan Parker should have made it 2-0 only to somehow shoot wide late on.
Oldham: Pogliacomi, Eardley, Haining, Gregan, Charlton (Rocastle 84), Liddell (Smalley 77), Wellens, McDonald (Edwards 78), Taylor, Porter, Warne.
Subs Not Used: Blayney, Lomax.
Blackpool: Rachubka, Barker, Evatt, Jackson, Coid, Gillett, Fox, Southern, Hoolahan (Forbes 79), Morrell (Parker 69), Burgess.
Subs Not Used: Vernon, Evans, Gorkss.
Booked: Hoolahan, Parker.
Goals: Morrell 67.
Ref: A Penn (W Midlands).