The Blues enjoyed the majority of possession and territory in the first half but found themselves nine points adrift at the break before Alex Cuthbert's try brought the home team back into it.
That was the first try Munster had conceded in 366 minutes and despite the Blues hammering at the door they could not find a second score.
However in the last play of the game full-back Dan Fish's pass to Cuthbert was adjudged forward - the third try they had ruled out by the officials - to the relief of Tony McGahan.
That meant Munster continued to top the RaboDirect PRO12 with four wins from four this season and their 14th consecutive victory overall.
An early Cardiff penalty was squandered by Ceri Sweeney, normally so reliable with the boot, after James Coughlan was pinged for not releasing.
Opposite number Keatley showed him how to do that as he immediately gave Munster the lead with a penalty from the halfway line only for Sweeney to miss another kick after the Blues had gone through 23 phases.
The Blues' frustration continued when a fabulous try-saving tackle by Denis Hurley just pulled Cuthbert into touch before he grounded the ball before the television match official ruled prop Sam Hobbs had grounded the ball short of the line.
Eventually Sweeney did open his account in the 19th minute only for Keatley to immediately restore Munster's advantage four minutes later.
The immaculate right foot of Keatley added two further penalties to put make the score 12-3 - a scoreline that did not necessarily reflect the balance of play.
But Cardiff got the try their territory and possession deserved early in the second half as captain Paul Tito offloaded to Cuthbert who steamed in to touch down.
Sweeney converted to make it a two-point lead but dissent in the Blues ranks led to Keatley immediately extending the lead to five.
Another Keatley penalty on 58 minutes took them a score ahead but with ten minutes remaining Munster were just able to halt Cuthbert in front of the posts, although illegally according to the referee. Sweeney's penalty gave the home team hope for a late comeback.
That hope was extended when Keatley was yellow carded with minutes left and the home crowd thought they had a famous victory to saviour when Cuthbert crossed in the corner - only for Fish's pass to be ruled forward.
|Cardiff Blues Score Card|
|Munster Rugby Score Card|