The Hatters missed out on a chance to put one foot in the play-off race; Nathan Jones' side would have drawn level on points with tonight's opponents if the result went their way.
Story of the match
Cardiff dominated possession in the opening stages but the Bluebirds were unable to convert that early pressure into any clear cut chances.
Simon Sluga came to the home side's rescue with 15 minutes on the clock; the Croatian was quick to drop down to his left and parry away Vaulks' low shot from outside of the penalty area.
Luton very nearly took the lead against the run of play. Following a superb delivery into the box from Tom Lockyer which found the head of Luton's danger man James Collins, however, the Irishman was unable to divert his diving header at the far post on target.
As the first half progressed the home side appeared to become progressively confident and began to control the play. With just over half hour gone Dillon Phillips found himself having to be light on his toes in order to tip Kiernan Dewsbury-Hall's powerful free-kick over the crossbar.
10 minutes before the break, the Bluebirds had a claim for a penalty after Matty Pearson pulled Josh Murphy down just inside the Luton 18-yard box. Referee Tim Robinson however did not see the situation in the same light as McCarthy's side.
After lacking any real attacking threat since the start of the match, Cardiff took the lead arguably undeserved. Wilson curled his left-footed effort from the edge of the box low and across goal into the bottom corner.
Minutes after, Wilson came agonisingly close to double the visitors' lead but was denied by a flying Sluga. From the resulting corner, Vaulks found himself being perfectly presented to hit a half-volley through a crowded penalty box and into the back of the net.
As any side who finds themselves two goals down should, Luton to take the game to Cardiff and started to control the game once again as they did for spells in the first half. Pelly-Ruddock Mpanzu had multiple half chances to test Phillips in the Cardiff goal but the 26-year-old was unable to hit the target.
Cardiff saw the game out rather comfortably to seal what could turn out to be a vital three points in the race for the play-offs
Takeaways from the match
McCarthy's men stubborn in defence
Despite tonight's win only being Cardiff's second clean sheet since McCarthy's arrival in the Welsh capital, the Bluebirds certainly have developed a stubbornness at the back.
Luton had a handful of opportunities which they could have beaten Phillips at least once, but Cardiff certainly had a resilience that was there for all to see.
This defensive form is something that any Cardiff fan would be pleased to see especially with them having a crunch game with fellow play-off rivals Bournemouth coming up on 24 February.
Harry Wilson composed as ever
The youngster possesses a particular composure that is hard to come by. Finishing like that, will certainly get him noticed by the Wales camp in the build up to the Euros.
If Cardiff's fine form continues Wilson will certainly benefit massively and could have a massive impact on 22-year-olds future; in terms of his time at Liverpool.
Man of the match
Harry Wilson didn't have the most to offer in the first half but he sprang into life in the second half.
Besides from the goal he was composed on the ball in the middle of the park and wasn't afraid to advance forward.