Goals in either half from captain Pat Purcell, Jeffrey Judge and Corie Treacy five minutes from time secured victory.
Purcell headed home on the half-hour and Judge netted a 20-yard rasper — helped by a deflection — 11 minutes later.
Noel Magee pulled one back on the hour when he gave Lims keeper Barry Ryan no chance following great work from Mark Sherlock on the right.
But Treacy put the matter beyond dispute in the 85th minute.
Lims now travel to meet high-flying Monaghan United in their penultimate game of the season next weekend, needing a win to have any hope of making the play-offs.
LIMERICK FC: Ryan, Bhandarker, Frost, Purcell, Treacy, Gamble, Judge, Gaffney, O’Flynn (Hynes 65) Sheedy (Brosnan 79) O’Leary (Tracy 67).
ATHLONE TOWN: Schlingerman, Rushe, Carr, Walshe inj (Danagher 17) Barrett, King, Hughes, Relihan, Sherlock, Williamson, McGee.
Referee: K Callanan (Cork).