The centre-back, who has been capped once by England, has joined the Premier League newcomers on a four-year deal to become Malky Mackay's fourth summer signing
The 21-year-old has signed a four-year deal with the Premier League newcomers, becoming manager Malky Mackay's fourth summer addition after Andreas Cornelius, Simon Moore and John Brayford.
Caulker enjoyed a successful breakthrough season at White Hart Lane last term, making 28 first-team appearances, but lost his place towards the end of the campaign - and is now ready to impress for his new side in their debut Premier League challenge.
"First and foremost I want to say how happy I am to have signed with Cardiff City," he told the club's official website. "I’m delighted to be here and excited for this fresh challenge.
"I spoke to [Mackay on Tuesday], liked what he had to say and am excited about the plans he has for the club. You get the sense of excitement from everybody at the club in the build-up to the season’s kick-off at West Ham and I’m really looking forward to being part of it.
"I thank Tottenham for everything they’ve done for me, having been there since I was a kid. But I'm here to back myself up now and show what I can do. This is a fresh start, a new chapter and I’m here to kick on.
Caulker, who scored on his senior England bow last year in a 4-2 loss friendly loss to Sweden, spent the 2011-12 season on loan at Cardiff's rivals Swansea.
Picture credited to Cardiff City's official Twitter page.