Burren captain Dan McCartan was sent off in the last minute of normal time when his side was leading 0-7 to 0-6. Kilcoo then hit three points in injury-time to retain the title, with Darragh O’Hanlon first converting a huge 50m free to draw the sides level in stoppage time.
Paul Devlin landed the winning free in the fourth minute of injury-time and tagged on an insurance point from play with the last kick of the game.
Kilcoo will now face the Armagh champions in an Ulster club quarter-final on November 3.
Defending champions Kilcoo edged a really mediocre first half by 0-4 to 0-3. Burren led 0-3 to 0-1 after 16 minutes with points from Jamie McGovern, a Donal O’Hare free and a James McGovern point.
Kilcoo only had a free from Paul Devlin to show for their efforts until they finished with three points in the last four minutes of the half.
Wing-back Darragh O’Hanlon ended their scoring drought when he burst through and hit a low shot across the goalkeeper.
The ball crashed off the upright but Ryan Johnston scooped up the rebound to score their first point from play in the 26th minute.
Conor Laverty’s point drew the sides level before Paul Devlin added a free just before the interval.
Burren didn’t score for 25 minutes either side of half-time but did lead by a point twice in the second-half.
However Kilcoo finished strongly, scoring one third of their entire tally in injury-time to retain the title.
Scorers for Kilcoo: P Devlin (0-5, 3f, 1 45), C Laverty (0-2), R Johnson, D O’Hanlon (f) (0-1 each).
Scorers for Burren: Jamie McGovern, D O’Hare (2f) (0-2 each), K McKernan, James McGovern, C McGovern (0-1 each).
KILCOO: S Kane; N Branagan, N McEvoy, D Branagan; D O’Hanlon, S O’Hanlon, Gerard McEvoy; P Greenan, A Branagan; P Devlin, A Devlin, R Johnston; J Johnston, C Laverty, Gary McEvoy.
Subs: F McGreevy for Gary McEvoy (52), Aaron Branagan for R Johnston (60).
BURREN: C Murdock; D McCartan, R McGovern, G McCartan; Jamie McGovern, K McKernan, James McGovern; C Toner, A McArdle; S Murdock, C McGovern, E Toner; D O’Hare, E McCartan, S McArdle.
Subs: Gerard McGovern for E McCartan (59).
Referee: Gavin Corrigan.