Ciara McAnespie and Catriona McConnell scored two goals each, while Caoimhe Mohan also found the back of the Donegal net as Monaghan ran out 5-16 to 1-05 winners.
McConnell (2-03) and McAnespie (2-02) rang rings around the Donegal defence.
Karen Guthrie converted a penalty for Donegal just before the break but by then Monaghan led by 2-09 to 0-03, with McAnespie and McConnell on target with first-half goals.
Monaghan are now almost certain to achieve a top-four finish, along with Dublin, Laois and Cork.
However Donegal are now in a relegation battle with Tyrone and Meath.
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