Mayo secured survival in Division 2B thanks to Padraig O'Flynn's 60th minute goal on Saturday in Carrick-on-Shannon.
Midfielder O'Flynn blasted home from 13 metres to seal the victory after taking a pass from top scorer Kenny Feeney.
Donegal actually led when Ronan McDermott powered to the net for a 1-4 to 0-6 advantage, with the influence of returned cruciate victim Danny Cullen very evident. Feeney and Lee Henderson were tit-for-tat with frees before Dylan Laverty made a telling save from Feeney.
Seven minutes before the break, Mayo netted when David Kenny set up Sean Regan, who fired into the roof of the net.
Donegal stayed in touch, but O'Flynn put the tie beyond them. Donegal had one late chance, but Kevin Campbell's tame penalty was saved by Donal O'Brien.
Tir Chonaill manager Ray Durack fumed at the refereeing afterwards. "I am very disappointed and the biggest problem we have at our level of hurling is the standard of refereeing," he said. "They are awarding frees for handbag stuff."
Man of the Match: Kenny Feeney (Mayo)
Scorers - Mayo: K Feeney 0-8 (7f), S Regan, P O'Flynn 1-0 each, S Boland 0-2, C Finn, B Hunt, D Kenny 0-1 each.
Donegal: L Henderson 0-7 (fs), R McDermott 1-1, C Matthewson, S McVeigh, D Cullen 0-1 each. Donegal: L Henderson 0-7 (fs), R McDermott 1-1, C Matthewson, S McVeigh, D Cullen 0-1 each.
Mayo - D O'Brien 7, E Collins 6, A Connolly 7, A Brennan 7; N Casey, J Kennedy, C Finn 7 ; D Kenny (0-1), P O'Flynn 7; K Kiely, K Feeney 8, F Boland; D McTigue 6, S Regan 7, S Boland 7. Subs: S Horley 7 for J Kennedy (18), B Hunt 6 for D McTigue (37).
Donegal - D Laverty 6; B Tourish 6, J Donnelly 6, M Callaghan 6; C McDermott 6, P Doherty 6, N Cleary 6; R McDermott 7, J O'Loughlin 6; E McDermott 6, S McVeigh 7, B Lafferty; L Henderson 8, K Campbell 7, D Cullen 8. Subs: C Matthewson 7 for J O'Loughlin (38), C Kilgannon 6 for Lafferty (39).
Ref - J Keane (Galway).