The Bluebirds now sit four points clear at the top after a blistering first-half display at the Cardiff City Stadium.
Perry Ng’s thunderous strike capped a dominant opening 45 minutes, but it was Colwill’s influence that underpinned the win, earning him man-of-the-match honours.
Head coach Brian Barry-Murphy admitted he had long been told about Ng’s eye for goal, yet this was the first time he had witnessed it firsthand.
“Perry is capable of producing a finish like he did today - so I'm told from previous seasons - so I'm glad to see it in the flesh,” said Barry-Murphy.
“I thought there was a pass on to Ollie Tanner, luckily he listened to the supporters and shot.”
READ MORE: Calum and Jack go Way Back . . . But this is Strictly Business at Cardiff City
Ng’s return has been timely. After injuring his knee on the opening day of pre-season, he had watched Ronan Kpakio impress in his absence.
Now fully fit, he is making up for lost time.
“He injured his knee on the first day of pre-season and Ronan Kpakio has been doing exceptionally well in his absence.
“It is a concern of mine that I haven't been able to play Ronan as much as I would have liked to because of the form of Perry, but that's the stage of the season we're in.
“All the lads at the back were really concentrated against a team who are dangerous. Luton can create and score goals, so I'm really pleased with how little we conceded against them.
“I'm over the moon with the performance. We started with great intensity, created good chances and scored enough of them to win the game.
“There have been different parts of the season that stick out, but against a team of this calibre we knew we had to be at our best and really pleasingly we were.”
READ MORE: Re-Born Joel Bagan is the Heartbeat of Cardiff City’s Revival
Cardiff struck first after 11 minutes when Colwill wriggled away from four defenders before delivering a sublime assist for David Turnbull to convert.
Luton responded from the penalty spot in the 19th minute after Joel Bagan felled Isaiah Jones, an incident that left Hatters boss Jack Wilshere frustrated.
“I thought it should have been a red card and a penalty. But the referee said to me the rule has changed because it was an attempt to play the ball,” said Wilshere.
“That’s subjective. I’ve been a player in certain moments when you know you can’t get the ball and you just try to make a foul.
“I’m frustrated, but we still have to do more. We didn’t have enough threat or enough shots – it was a tough day.
“We didn’t do too much wrong up until those 10 minutes before half time. Then we gave the ball away and they scored and then they got a wonder goal.”
READ MORE: “Is it Because I is Welsh?” . . . Cardiff City Boss Goes Full Ali G
Wilshere’s side were undone late in the half as Colwill restored Cardiff’s advantage with a composed finish from the edge of the area, wrong-footing goalkeeper Josh Keeley for his fifth league goal of the campaign.
Ng’s spectacular third soon followed, giving the hosts control they would not relinquish.
For Barry-Murphy, Colwill’s display symbolised the progress being made by the 21-year-old midfielder.
"Joel Colwill's game is improving so much, he has such a hunger to improve," added the Cardiff boss.
"The parts of his game we feel are important to give him the outcomes that he got today are the bits he has been working on.
"He arrives in the box all the time and because of that he has to have the ability to make the correct decision.
"He has the technical ability to make it happen like he did today."
While pleased with his individual contribution — a goal and an assist in Cardiff’s 13th home league win from 16 — Colwill was keen to emphasise the collective effort.
"It was a really good afternoon, we all gave a good account of ourselves," said Colwill.
"Anything to help the team is a really positive thing, I'm obviously glad to score and assist but ultimately it was the team performance which got us over the line today."
The afternoon also marked the welcome return of his older brother Rubin Colwill, who featured for the final 20 minutes after recovering from an ankle injury sustained in November.
Cardiff have remained top since that victory at Northampton, and both player and manager believe Rubin’s comeback could provide another lift for the run-in.
"It's really good to see him back," said Joel.
"He had a brilliant first quarter of the season before he got injured and he's going to have a brilliant second half, I'm really excited to see what he brings.
"Having him back will help boost us and get over the line."
Barry-Murphy echoed that optimism.
"Rubin is a huge figure in our team and for the club.
"He's come back in incredible condition. It's about how much we want to expose him to and how soon.
"I think today was about the right amount of time and he'll improve for it."
