NUI Galway's gutsy second-half comeback proved in vain as Sligo edged home for a second successive win thanks to three points from Niall Murphy in the last 10 minutes at Tourlestrane.
Sligo can reach the final with a win over manager Kevin Walsh's native county Galway this weekend.
NUI Galway recovered bravely from an interval deficit of 0-10 to 0-4 to draw level, 1-7 to 0-10, after 43 minutes.
Kieran Murtagh (2) and Ian Galvin both pointed during this revival while Cathal Freeman's netted a 37th-minute goal.
NUIG moved in front when Shane Nally pointed from long range in the 48th minute but Sligo, now trailing 1-9 to 0-11, swooped for the next three scores, all from the impressive Murphy.
Sligo enjoyed an excellent first-half after a sluggish start – Kenneth Sweeney emerged as their most potent attacker in that opening period with four points.
The home side's best goal chance was an opportunity for Tourlestrane's Brian Egan, who, on his home pitch, blasted a 29th-minute shot wide of Donal O'Sullivan's left-hand upright.
Scorers – Sligo: N Murphy 0-5 (4f), K Sweeney 0-4, B Egan 0-3 (1f), M Breheny (f), J Clarke 0-1 each. NUI Galway: C Freeman 1-2, I Galvin (1f), K Murtagh (1f) 0-2 each, M Kelly, F Ó Deasmhunaigh, S Nally 0-1 each.
Sligo – B McGovern; A Brennan, J Martyn, J Kelly; N Ewing, A McIntyre, B Curran; J Clarke, E Mullen; Brendan Egan, N Murphy, S McManus; Brian Egan, M Breheny, K Sweeney. Subs: P Greene for B McGovern (h-t), K Cawley for N Ewing (h-t), C Harrison for A Brennan (44), S Gilmartin for S McManus (49).
NUI Galway – D O'Sullivan; A Tierney, C McDonald, K Crowe; G Sweeney, D Gavin, C Walsh; J Moloney, S Moran; S Nally, F O Deasmhunaigh, C Freeman; I Galvin, M Kelly, K Murtagh. Subs: E O Hocaigh for J Moloney (11), E Troy for C Walsh (24), N Freeman for A Tierney (35), S Moran for M Kelly (51), C Brennan for E Troy (58).
Ref – D Corcoran (Mayo)