Peter Hutton’s side claimed their first win of the season over the Midlanders and have secured the fourth place spot in the league standings.
Striker Paul McVeigh continued his rich run when he netted for the fifth time in nine outings to give Harps the lead.
McVeigh picked up on a poor back-pas by Athlone to nip in and give Harps a half-time advantage.
And when veteran striker Kevin McHugh made it 2-0 after the break from 12 yards, the points were in the bag barring a disaster.
Athlone did rally towards the last quarter but Harps defence held solid to claim a deserved victory.