The Tralee side led 0-8 to 0-3 at half-time, but had to rely on a Declan Quill free three minutes into injury-time at the end of the game to finally see off Kilcummin.
The decision to place veteran Michael McCarthy in the half forward line for the second half reaped rich dividends for Kilcummin, with the former Kerry defender inspiring their fightback.
McCarthy set up DJ Fleming for his side’s second goal, which put Kilcummin in front for the first time, 2-5 to 0-10.
But Kerins’s O’Rahillys, inspired by Quill and Barry John Keane, who converted a second-half penalty, held their nerve to carve out a win
Scorers for Kerins O’Rahillys: D Quill 0-5, (4f), BJ Keane 1-3 (1-0 pen, 1f), JC O’Connor 0-1, R Molloy 0-1, J Savage 0-1, D Flaherty 0-1.
Scorers for Kilcummin: DJ Fleming 1-5 (4f), I Devane 1-0, M McCarthy 0-1, C O’Leary 0-1, K Gorman 0-1.
KERINS O’RAHILLYS: D Hennessy; D O’Sullivan, S Brosnan, M Tierney; A Thompson, B Moran, G O’Grady; M Quirke, JC O’Connor; R Molloy, J O’Connor, D Flaherty; D Quill, BJ Keane, J Savage.
Sub: G Kissane for A Thompson (53).
KILCUMMIN: B Kealy; T Brosnan, K McSweeney, S Brosnan; C O’Leary, M McCarthy, Damien O’Leary; S McSweeney, K Gorman; N Duggan, Daniel O’Leary, I Devane; DJ Fleming, K Murphy, J Sheehan.
Subs: G O’Leary for J Sheehan (27), J Devane for N Duggan (h-t).
Referee: G Carroll (Asdee).