We are delighted to welcome Jack Kingdon to the Bluebirds, who will link up with Darren Purse's U21 side.
The defender arrives in the Welsh capital from Manchester United, where he gained experience out on loan at Rochdale.
The 19-year-old has also regularly featured in the U18 Premier League and the Premier League 2 on his way to joining City.
Jack's arrival is our fourth signing at U21 level this summer, following the additions of Gabriel Keita, Charlie O'Brien and Matthew Apter.
Upon signing for the Club, Jack said: "I'm really excited to join a Club with such great history and I can't wait to get going. I'm a very hard-working player who will always give my all for the team.
"I went on loan to Rochdale, which was a good experience because it gave me a taste of men's football. That helped me to learn my trade.
"I've looked at our recent results at U21 level and they're positive. The team are scoring a lot of goals and keeping clean sheets, so I'm looking forward to playing with them.
"At First Team level, you can see young players making debuts and establishing themselves. I just want to be a part of that."