Laois had raced into a five points to one lead early in the first half, aided by a strong wind in Crettyard.
Although Donegal pulled a goal back, Laois led 1-08 to 1-02 at the break.
The hosts increased their lead in the second half, with two more Donegal goals keeping them in touch.
But Laois piled on more points to win 2-18 to 3-05.