Liverpool ended its six-year trophy drought 2 in a shootout after a 2-2 draw at Wembley Stadium.
Cardiff led early through Joe Mason and answered Dirk Kuyt's goal in the 118th minute through Ben Turner, but had two penalties hit the post and another sail wide as Liverpool escaped with the trophy.
Martin Skrtel scored for Liverpool in normal time, erasing Mason's 19th-minute goal when he drove in a rebound after Luis Suarez headed off the right post on the hour mark.
Kenny Miller had a chance to win it for Cardiff in the 88th, but he lifted his golden chance over the bar with just Pepe Reina to beat, and Liverpool pounced in extra time.
Suarez had a chance cleared off the line by Andrew Taylor early in the opening extra session, but substitute Kuyt was not to be denied early in the second OT session.
Kuyt directed his own rebound into the net in the 108th, but Cardiff would not die and added the late equalizer when Turner scored.
With Kuyt marking him on the back post, a loose ball fell to Turner and he was able to poke the ball through Reina's legs to tie the match.
Cardiff goalie Tom Heaton made a huge save on the first penalty from Liverpool with a diving save to his right. Heaton pushed Steven Gerrard's shot off the crossbar, but Miller followed with a shot off the right post for Cardiff.
Charlie Adam lifted Liverpool's second attempt high, and Don Cowie put Cardiff in front when he converted to the upper-left corner. Kuyt was on target to tie the shootout, and Rudy Gestede then hit the left post for Cardiff.
Liverpool's Stewart Downing and Cardiff's Peter Whittingham both converted in the fourth round, and Glen Johnson followed with another conversion for the Reds to put all the pressure on Cardiff's Anthony Gerrard.
Anthony Gerrard, the cousin of Steven Gerrard, drove his attempt wide left and Liverpool celebrated the trophy over the Championship side. Liverpool last won a Cup in 2006, when it lifted the FA Cup.
Liverpool has won the Carling Cup, or League Cup, eight times.