More than a million-and-a-half viewers fell in love with Callum and his 'hype man' brother Jackson (five) as they got the crowd cheering and dancing along.
And the Dublin brothers' hilarious reaction to a young opera singer on the show has gone viral and inspired hundreds of memes on social media.
Speaking to the Sunday World, Callum says he was stunned when he heard opera singer Fergal O'Shaughnessy (16), from Co. Tipperary, break into an stunning version of Ava Maria.
"I was just totally amazed because he sounded like a grown up, but he was only a kid and nearly the same age as me. He was unbelievable," says Callum.
As for his face-pulling becoming a huge viral hit, he laughs: "I've had a lot of slagging over it!"
Radio stars Tracey Clifford and Marty Guilfoyle have already contacted Callum to go on their shows after his barnstorming set on The Late Late Show on Friday night.
But the young Dub has already forged links with former 2FM DJ McCabe.
Rave legend McCabe has the fifth-biggest selling single of all time in Ireland with his 2000 remix of the famous Flashdance hit, Maniac, and has had Callum a couple of times on his I-Radio show having spotted the Dubliner's talent even at the age of 11.
"In August or September, Callum put his first one-hour techno mix on his YouTube and he has been on I Radio two or three times since, Mark McCabe had him on first," Callum's dad David Kieran tells the Sunday World.
"Mark trusted him and brought him on and Mark has been great with him and texted him back and forward saying 'if you need anything I'm here and if you're unsure of anything'.
"Mark got him on first and smashed it and then had him on again and he smashed it again.
"He's been on since The Late Late and is thrilled for Callum," David (36) says.
Callum and his brother appeared on Friday's Toy Show with superstar Ed Sheeran and Olympic gold medal winner Kellie Harrington also making surprise appearances on the show which has already raised €5 million for charity.
Callum hit the decks for a pulsating routine which saw a selection of dancers performing a variety of moves while Jackson got them going.
It was thanks to David attending the Tomorrowland dance festival in England that Callum and Jackson fell in love with music.
David says that Callum was inspired by a video of a superstar DJ.
"When I came back, obviously Jackson was a lot younger, but I was showing Callum that I was at a set by DJ Armin Van Buuren," recalls physiotherapist David.
"He just loved it. So, he never stopped watching. Between him and Jackson they had YouTube on all the time playing DJ sets.
"I remember Callum saying to me 'Dad I'd love to be a DJ, that looks amazing, look at all those people, they are all looking up at that DJ."
David and the boys' mum Kirsty got Callum a set of decks for his ninth birthday.
"I didn't get to use them for about a year, but then last summer I got to use them then because my dad had time to help me with the basics," an excited Callum tells us. "I'm still learning but I'm getting there."
David reveals that lockdown helped them.
"During the first one in March last year I had three months off and he said: 'Dad can we learn music, can you help me learn the basics?'," he recalls.
"So, I hadn't a clue, but we learned it. Both of us spent a lot of quality time and put a lot of effort into learning how it works."
The family lives in Finglas on Dublin's northside and the boys go to Gaelscoil Uí Earcáin.
Not only is Callum a blossoming DJ but he also trains in MMA in Charleston SBJ, boxes in Ballybough club and plays scrum-half in rugby for Cooolmine.
"I'd love to be a professional rugby player and a DJ," Callum smiles.
The two lads are now trying out the new equipment in their attic, which host Ryan Tubridy presented them with on behalf of One Sonic.
This year's Toy Show had a 'Lion King' jungle feel to it, kicking off with a dance routine from Canon Mooney flats in Ringsend, Dublin, and the children and audience members who took part in the two-and-a-half-hour show dressed up as various animal characters.
Revolut had some problems with viewers trying to make donations and the company has now made an initial donation of €100,000 and will match up to €1million if the same sum is donated over the next 24 hours.
Donations can be made via
www.rte.ie/toyshowappeal and proceeds can also be made on the Revolut app which will go live on the night.