Antrim failed to score after the break at sun-baked Clones as they limped out of the series.
Padraic Keenan and Fergal McGeough combined to send Conor McCarthy in for a Monaghan goal after just three minutes.
And the Farney men went six points clear when David McAllister netted after 10 minutes.
But they failed to score in the remainder of the half, and the Saffrons were right back in it when Eoin Fleming slotted home a 28th minute penalty. Monaghan led 2-1 to 1-2 at the interval, and swept over nine quality points in the second half, the best of them from James McElroy and McAllister.
Scorers for Monaghan: C McCarthy, D McAllister 1-1 each, P Keenan 0-3 (3f), F McGeough 0-2, J McElroy, A Treanor, C Lavelle 0-1 each.
Scorers for Antrim: E Fleming 1-0 (pen), D McAleese, M Cummings 0-1 each.
MONAGHAN: D Kirk, B Hanratty, S Conlon, R Wylie, F Malone, M McGee, P Keenan, B Greenan, J McElroy, F McGeough, S Buckley, C McCarthy, A Treanor, D McAllister, R McAnespie.
Subs: K Rudden for McAnespie, D McElroy for Buckley, C Lavelle for McGeough, D Ward for McAllister, S Mohan for Treanor.
ANTRIM: T Hughes, C Quigg, S Gorman, C O’Rawe, M Fitzpatrick, R Wilson, J Hannigan, M Cummings, R McCafferty, D Doherty, M Lappin, D McAleese, E Fleming, D Trainor, P McAleer.
Subs: J Gallagher for Hannigan, J Scullion for McAleer, R McCann for Lappin, J O’Connell for Fleming.
Referee: I Molloy (Donegal).
Derry 2-9 Donegal 1-7
By Tom O’Neill
Terence O’Brien helped himself to two goals as Derry coasted into the Ulster MFC semi-finals at Healy Park last night.
Just 90 seconds had elapsed when O’Brien dispossessed goalkeeper Daniel Mullarkey to slot home a goal from close range. Ryan McHugh and Conor Harkin hit Donegal points, but with Peter Cassidy putting in a mighty shift at midfield, it was the Oak Leafers who held the upper hand. Cassidy fired over a couple of gems, and Gerard Bradley also scored twice.
But Donegal showed their battling qualities for Stephen McBrearty to turn over possession and send Ryan McHugh in for a superb score. O’Brien stroked over a ’45 in stoppage time to send Derry in with a 1-6 to 0-4 interval lead.
Bradley added another couple to his tally and sent O’Brien through for his second goal, finished clinically to the top corner of the net in the 39th minute.
Donegal pulled back a goal from a penalty through skipper Ryan McHugh. They trimmed the deficit further through Hugh McFadden and John McGarvey, but their challenge fell short.
Scorers for Derry: T O’Brien 2-1 (0-1 ’45), G Bradley 0-4 (1f), P Cassidy 0-2, R McDonnelly, R Bell 0-1 each
Scorers for Donegal: R McHugh 1-2 (1-0 pen, 0-1f), C Harkin (1f), J McGarvey 0-2 each, H McFadden 0-1.
DERRY: C Bradley, D Brown, M Sweeney, G Doyle, G McKinless, C McAtamney, C Carville, P Cassidy, R McDonnell, J Kearney, C McFaul, T O’Brien, G Bradley, R Bell, R Moore.
Subs: C Gallagher for McKinless, R Dougan for Moore, A McNicholl for Kearney
DONEGAL: D Mullarkey, G Kelly, C Parke, J Rose, S McBrearty, M Gallagher, D Mulgrew, B McNelis, R McNamee, C Harkin, J McGarvey, A McGinley, R McHugh, W Gillespie, E McHugh.
Subs: H McFadden for McGinley, S Fitzgerald for Rose, C McGettigan for McGarvey, C Gallagher for Gillespie
Referee: B Rice (Down).