Peamount took the lead in the fourth minute when Eleanor Ryan Doyle headed home from close range after good work by Chloe Murphy.
Listowel had a lengthy spell of dominance in the first half but failed to trouble United keeper Amy Corcoran although a brilliant strike by Niamh Carmody seven minutes into the second half was a signal of their attacking threat.
Peamount skipper Rachel Doyle was a massive influence on the game with her dead-ball deliveries and it was from her 49th minute cross that Chloe Murphy had a header saved from point blank range.
Doyle then made it 2-0 with a stunning 22-yard free-kick that flew in off the inside of the Celtic post to put Peamount in control.
Listowel got back in the game in the 70th minute when Aoife Shine's right wing cross went over the head of Corcoran and landed in the Peamount net.
Celtic skipper Rebecca Horgan went desperately close to levelling matters in the 74th minute when he was sent through on goal only to see her slipped effort slide the wrong side of the Peamount upright.
Peamount sealed the victory with three minutes left when substitute Erin Best produced a brilliant shot from distance that the impressive Listowel keeper Tina Mangan could do little to keep out.
LISTOWEL CELTIC: Tina Mangan; Alice Brislane, Louise Horgan, Megan Carroll, Aislinn Kelliher, Megan O'Connor, Aoife Shine, Savanna McCarthy, Rebecca Horgan, Erin Finucane, Niamh Carmody (Ashley O'Brien 60).
Substitutes: Megan Fealey, Kylie Walsh, Caoimhe Dowling, Charlotte O'Neill, Sarah Treacy, Colette Foley.
PEAMOUNT UNITED: Amy Corcoran; Ciara Walsh (Shauna Bates 54), Rachel Doyle, Emilie Ryan Doyle, Lauren Kealy, Hayley Nolan, Rebekah Carroll, Chloe Murphy (Celina Forde 65), Eleanor Ryan Doyle, Danie Murray (Ashling Driver 77), Chloe Silke (Erin Best 45).
Substitutes: Eilis Boyle, Hayleigh Higgins, Ciara Lacey.
Referee: Owen Moynihan.
17-05-2013 - National and International Fixture List (May 18 - 29)
17-05-2013 - Bus Ã‰ireann Women's National League Cup Final on Sunday
15-05-2013 - Oâ€™Connorâ€™s U16s march home with another victory
15-05-2013 - Germany U16s trounce Romania 10-1
15-05-2013 - Noel King names 16 man U21 squad to face Denmark on May 31
14-05-2013 - Bus Ã‰ireann National Women's League Awards presented
13-05-2013 - U16s lose to Romania in UEFA Development Tournament
12-05-2013 - Raheny United crowned Bus Ã‰ireann Women's National League champions
12-05-2013 - O'Connor's U16s start tournament with win over Germany
11-05-2013 - Bus Eireann WNL title race goes down to the wire