He’s agreed a two-year deal with a club option to extend by a further 12 months.
The Canaries brought 19-year-old Rylee Mitchell in from Stevenage last month, mirroring a first team reshuffle that has included three senior arrivals.
Lines will now join Mitchell as part of Olly Lee’s development squad, freeing young talents in a bloated department up to secure loans away from Colney in the 2025-26 season.
Lines, 18, first played for Coventry’s under-21 side in 2023, and has gone on to make four FA Youth Cup appearances for the Sky Blues. He’s also played for Wales at under-17 and under-18 levels.
Speaking to official club channels about the move, he said: “I’m happy to be here. It’s good to get the deal done and I can’t wait to get started.
“I’m looking forward to pre-season, I want to get settled down in the club and get underway as quickly as possible and work hard.
“This season I just want to get as many minutes as I can, push myself as much as possible, then of course first team is always the goal. I’ll take all the opportunities I can.
“Playing for Wales was an amazing experience, I went to the Under-17s Euros in Cyprus. That was probably the best experience of my life, being around top players in Europe, Chido Obi for example. That was a fantastic experience.”
City’s under-21s kick off their pre-season campaign next Tuesday when they travel to face Colchester United.