Career
Early career
Ralls played for Aldershot Town, where he played one game in the Aldershot Senior Cup tie against Bagshot, before joining Farnborough under-16s. After he was spotted by Cardiff City scouts along with Jordan Carter, a small compensation was paid by Cardiff to sign the two players. He agreed to play in a trial match for Premier League side Fulham, although this was postponed before he joined Cardiff.
Cardiff City
Ralls made his first team debut against Oxford United in the League Cup on 10 August 2011.
His first start came against Huddersfield Town 13 days later. He signed his first professional contract on 30 September.
Ralls made his league debut a day later against Hull City, where he also scored a stunning volley for his debut goal. His first league start came on 10 December in a goalless draw at Millwall.
In the 2012/2013 pre-season friendlies, Ralls scored the second goal in a 4–1 victory against Premier League team Newcastle United.
He started the first competitive match of the season against Northampton Town in the League Cup. On 17 November 2012, Ralls filled in at left-back following an injury to Andrew Taylor as City saw off Middlesbrough 1–0 at Cardiff City Stadium. = Loan to Yeovil Town On 14 August 2013, Ralls moved to Football League Championship side Yeovil Town on loan until January 2014 in order to gain first team opportunities and experience.
On 11 January 2014, Ralls extended his loan with Yeovil until the end of the season.
= Return to Cardiff Under new Cardiff boss Russell Slade, Ralls became a regular in the first team during the 2014-2015 season, altogether playing 31 games and scoring 4 goals. At the start of the following season, he was handed the number 8 shirt and started in the left sided midfield role against Fulham on the opening day.
Ralls received his first international call for the England Under-19s to replace the injured Robert Hall to play Czechoslovakian Republic in February. Ralls came on in the games to make his English debut.