Last year's beaten finalists turned the tables on Birr in an impressive performance.
St Cillian's are Senior A Camogie champions of Offaly for the first time.
Last year's beaten finalists managed to reverse the result of their loss 12 month ago against Birr to beat the same opposition on a final scoreline of 1-10 to 1-5.
Much of the leg work was done by Cillian's in an excellent first half performance that saw them reach the break 1-7 to 0-3 ahead of back to back champions.
Birr did strike back with an early second half goal but the two clubs went score for score from that point on.
Claire Hogan top scored for the winners with 8 points, six of which were from deadballs.