Monaghan were on top throughout, even if some poor finishing prevented them from making it count. The hosts eventually pulled away when Christopher McGuinness scored the only goal of the game in the 45th minute.
An Owen Duffy point for Monaghan was the only score of a scrappy opening quarter, before he eventually added a second on 21 minutes. Adrian Marren got Sligo off the mark a minute later and although Paul Finlay replied from a free, Marren kicked another fine score to keep Sligo in touch.
Monaghan though finished the first half strongly and hit three unanswered points through Kieran Hughes (two) and Dick Clerkin to lead 0-6 to 0-2 at the break.
Monaghan got the first score of the second half from a 45 by goalkeeper Rory Beggan, but Sligo quickly responded through Niall Murphy. A third Kieran Hughes point kept Monaghan ahead and they took control when a well-worked move put McGuinness through.
Tommy Freeman and DIT Sigerson captain Colin Walshe swapped scores with Marren three times before McGuinness rounded off the scoring in injury-time to set up a top of the table clash with Fermanagh.
MONAGHAN: R Beggan (0-1, 45); K Duffy, D Mone, F Kelly; K O’Connell, N McAdam, C Walshe (0-1); O Lennon, D Clerkin (0-1); G Doogan, K Hughes (0-3), O Duffy (0-2); C McGuinness (1-1), P Finlay (0-1f), T Freeman (0-2f)
Sub: S Smyth for T Freeman (63).
SLIGO: P Greene; C Harrison, J Martin, R Donovan; N Ewing, A McIntyre, M Quinn; S Gilmartin, S McManus; M Breheny, P Hughes B Curran; B Egan, N Murphy (0-1), A Marren (0-6, 2f).
Subs: F Quinn for B Curran (34), J Kelly for B Egan (ht), B McGovern for P Greene (inj 46), J Kilcullen for M Breheny (49), K Cawley for N Ewing (inj 57).
Referee: S McLaughlin (Donegal).