The pair played together at Burnley.
New Blues signing Tarkowski told evertontv: “I didn't actually speak to him before joining, just because I didn't want to open my mouth too early. But, speaking to him through the years, I know how much he loves this club and know how big the Club is just from speaking to him. I know what I've got here and I look forward to it.
“It's nice to join up with him again and I look forward to seeing him.
“Of course, there's some very good players here. I've played with Keano, I know how good he is, and I've played against other lads here.
“Competition is important, it pushes you on and makes you want to play better, so I look forward to getting out there and training with the lads. It's a squad game so everyone is in it together for a successful season."