The 21-year-old centre-back joined the Bluebirds from Tottenham in an B£8million deal on Wednesday, putting pen to paper on a four-year contract at Cardiff City Stadium.
The deal was a real coup for Cardiff boss Malky Mackay, with Caulker regarded as one of the best young defenders in Britain.
Caulker, who has one England cap to his name, made 28 appearances in total for Spurs last season but felt he needed to be first-choice at a Premier League club to fulfil his ambition of being part of Roy Hodgson's plans in Brazil next summer.
He said: "If you ask any English player, they have got one eye on the World Cup.
"First and foremost I am going to have to work hard on and off the pitch to earn that sort of achievement, but it is something I am definitely working towards.
"It wasn't that I wanted to leave Tottenham but I am at a stage in my career where I want to play regular football.
"Spurs have three fantastic centre-halves and it may have been a case of being fourth-choice this season and not getting as many games as I would have liked.
"I didn't want to put my career on hold, I wanted to get out and get as much experience as possible and these opportunities don't come around very often.
"I want to help Cardiff progress as a team and progress myself."