Playing in the city of his birth, the Welshman rose from the bench in the 73rd minute and immediately caught the eye with a first-time through ball for Danny Welbeck, who shot over.
It was Giggs also who led United's vain charge for a winning goal after Cardiff's Kim Bokyung had made it 2-2 in stoppage time, lofting a delicately weighted 50-yard pass into the path of Wayne Rooney, only for the United striker to botch the opportunity by electing to pass.
Alex Ferguson may have stepped down as manager after 26-and-a-half long, glorious years and United may have fallen off the pace under his successor David Moyes, but the ageless Giggs bounds on regardless.
"The best thing is to say he doesn't play like he's 40 and he doesn't look like he's 40," Moyes said recently.
"He's an outstanding player and it's a privilege to be working with him on my staff, but also to have him as a player. I've seen something different since I've come here - just how good he is, close up - and it's incredible."
Giggs is starting to cast an eye towards the future, having been enrolled on United's coaching staff following Moyes's arrival from Everton, while he recently opened a London restaurant with former team-mate Gary Neville.
However, although his current United contract is due to expire in June, he says he has had no thoughts about turning the page on his playing career.
Asked by Neville during a recent television interview whether the approach of his fifth decade had brought retirement into sharper focus, he said: "I've never been guided really by the age.
"It's just about how I felt, if I'm contributing, if I'm still getting picked, still enjoying it. That's the sort of markers that I look for and all those things I feel like I'm doing.
"I could probably contribute a little bit more, but hopefully that will come as the season goes on. But no, just because I've turned 40 doesn't mean that's it.
"If I felt like that, then I might as well just pack it in now, but I still feel good and I'm still enjoying it."
Giggs is used sparingly these days and has played in only five of United's 12 league games to date this season, but he is already certain to leave a historic legacy.
He is United's record appearance-maker with 953 games and counting, and with 13 league titles, two UEFA Champions League trophies, four FA Cups and three League Cups to his name - as well as a clutch of other prizes - he is the most decorated footballer in the history of the English game.
A devilish tormentor of opposition right-backs when he blazed onto the scene as a jet-heeled winger in the early-1990s, Giggs has refined his game in recent years and now operates more often than not as an elegant midfield playmaker.
As a youngster, he was dogged by hamstring injuries, but he attributes his longevity to the discovery of yoga techniques that have helped him steer clear of the treatment tables in his latter years.
"The yoga has definitely helped me," he told La Gazetta Dello Sport last year. "It helps me train every day because it gives me the flexibility and the strength not only to play the game, but to train as well."
Giggs' famed hunger for success is unlikely to diminish in the months ahead, particularly with United currently seven points behind leaders Arsenal in the Premier League.
He will also be eager to maintain a run of scoring in consecutive league seasons that extends all the way back to 1991 - before some of his current team-mates were even born.