Leading by two points with nine minutes left, manager-less Leitrim couldn't sustain a remarkable effort, and Donegal scored seven points in the final quarter to ensure their survival in Division One.
Tony Boyle and Brendan Devenney offered a constant threat for Donegal, between them scoring 2-7, with wonderful finisher Devenney scoring two goals.
Donegal opened well in dreadful conditions, and led 1-3 to no score after 14 minutes, Devenney slicing through to score a close-range goal.
Leitrim were in some disarray, and not helped by the forced substitutions of Gareth Foley and his replacement, Fintan McBrien, both injured in the first 10 minutes. Undaunted, the visitors fought back, scoring five points in a row, two of them inside a minute from Aidan Rooney, and their best score, a long-range point from Jason Ward.
Tony Boyle gave Donegal a slender 1-4 to 0-6 half-time lead, but Leitrim sub Donal Brennan levelled 44 seconds into the new half.
Devenney scored a wonderful second goal, his venomous 25-metre drive a marvellous individual effort. Still, Leitrim battled, recent difficulties put behind them as Rooney levelled again, this time from a penalty.
Best at midfield, Leitrim went ahead 1-9 to 2-4 by the 41st minute, but failed to score again.
Donegal substitute Mark Crossan improved their defence, and points from Devenney and Boyle levelled the scores. Jim McGuinness finally broke their monopoly on Donegal scoring with an extravagant long-range point which put Donegal ahead again.
Impressive in a gritty sense, Donegal dug out four more scores to win by a flattering five-point margin.
Donegal: T Blake; D Diver, E Reddin, N McGinley; O Reid, N Hegarty (0-1), N McCready; J McGuinness (0-1), J Ruane; B Roper, A Sweeney (0-1), B Ward; J Duffy, T Boyle (0-5, three frees), B Devenney (2-2). Subs: S Carr (0- 1) for Ward; M Crossan for Reid; B McLaughlin for Roper.
Leitrim: G Phelan; J Phelan, S Quinn, P Flynn; C Regan, C Murray, G Foley; J Ward (0-1), C Carroll; P Farrell (0-2, frees), D McNulty, A Charles; B Guckian, C McGlynn (0-1), A Rooney (1-3, goal from pen). Subs: F McBrien for G Phelan; D Brennan (0-2) for McBrien; A Fee for Flynn .
Referee: P O'Toole, Longford.