Edinburgh flew out of the traps in the second half and replacement prop WP Nel burrowed over for a converted score before replacement fly-half Harry Leonard booted the hosts ahead.
But fittingly it was Patchell who settled the contest, the 19-year-old converting a penalty after a fine break from wing Harry Robinson to deliver the Blues their third win in four RaboDirect PRO12 games.
Edinburgh had the chance to take an early lead when Blues back row Josh Navidi was penalised for hands in the ruck but Gregor Hunter was wide with his penalty attempt.
Young Blues fly-half Patchell punished the miss on five minutes when he kicked the visitors into a 3-0 lead after a penalty at the scrum.
That triggered a spell of Cardiff pressure and while Edinburgh prevented the Blues from crossing the whitewash they gave Patchell a second penalty that he sent over on 13 minutes.
Fine play from centre Ben Atiga took Edinburgh into Cardiff territory but Hunter was unable to kick the penalty after the visitors were penalised.
A great step from Nick De Luca, returning from injury, opened up the Blues' defence but after the ball was recycled David Denton failed to find Dougie Fife with the try line in sight.
Edinburgh were on the board in the 25th minute when Hunter made it third time lucky but Patchell immediately added his third penalty of the game to make the score 9-3 to the visitors.
Hunter then failed with a long-range attempt but converted a more straightforward kick on 34 minutes.
However the Blues had the last word on the half when Patchell dropped the shoulder to beat his man and feed Paterson who crossed for the first try of the game, and while the fly-half missed the conversion, they led 14-6 at the break.
Prop Nel was one of two replacements made by Edinburgh at the break and the 26-year-old burrowed over from short-range ten minutes into the second half to put the hosts right back in the game.
Hunter slotted the conversion to put Edinburgh within a point of the visitors and his replacement Leonard kicked the home side ahead after the Blues were penalised at the scrum.
Both sides began searching for the crucial next score and after a fine break from Robinson it was a penalty from the boot of Patchell that edged Cardiff back ahead.
Leonard's missed pass looked to have put Edinburgh in only for replacement wing Tom Brown to knock on with the try-line gaping as Cardiff held on to win.
|Edinburgh Rugby Score Card|
|Cardiff Blues Score Card|