After impressing in an Urdd tournament as a youngster he signed for Cardiff City, who beat off competition from Newcastle United, as a schoolboy at the age of eight working his way through the club's youth system eventually making his Cardiff City debut in the last home game of the 2006-07 Championship season, coming on to replace Paul Parry in the final minute of the 1-0 defeat to Hull City on 28 April 2007. In doing so, Ramsey became the youngest player to ever play for Cardiff City, aged just 16 years and 124 days, beating the previous record holder John Toshack.
In June 2007, Cardiff City turned down a bid of over Â£1m for Ramsey from a London-based Premier League club. The club has not been named, but it is widely believed that they have continued to watch Ramsey at every available opportunity during the 2007-08 season. Cardiff also turned down a Â£1m offer, although the deal was to start with a payment of Â£200,000 and rise depending on his future achievements, from Everton and their Merseyside rivals Liverpool are also watching the youngster.
He made his first league appearance of the 2007/08 season on 6 October when he came on as a late substitute for Jimmy Floyd Hasselbaink in the 2-1 home win over Burnley. Ramsey signed his first professional contract in December 2007. On 5 January 2008 Ramsey made his first full professional start for Cardiff in the FA Cup against non-league side Chasetown replacing the suspended Stephen McPhail. An impressive performance from Ramsey saw him head in the second Cardiff goal as they went on to win 3-1. Due to his performance against Chasetown Ramsey was nominated for the Player Of The Round award, eventually losing out to Coventry's Michael Mifsud. He went on to make his first career league start three weeks later in a 3-1 win over Queens Park Rangers and began to establish himself in the first team making several more starts in the Cardiff side.
Following Ramsey's impressive performance in the 2-0 FA Cup quarter-final win over Middlesbrough it was revealed that Manchester United manager Sir Alex Ferguson had talked to Cardiff boss Dave Jones to enquire about Ramsey, joining Arsenal, Newcastle United and Everton in following his progress