Blake joined local youth side Jubilee Thistle at the age of nine where he played as a striker. At the age of 10, Blake joined the youth academy at Cardiff City, the club he supported alongside Liverpool, although he continued playing for Thistle until he was 12. After progressing through the club's youth system, he signed his first professional contract at the club in 2006 with a three-year deal, along with fellow academy graduate Chris Gunter. Blake made his professional debut on 17 April 2006 against Crewe Alexandra in the Football League Championship, following injuries to several first team players, replacing Jeff Whitley as a late substitute during a 1–1 draw. The following season, Blake was involved in the first team early, making two appearances in the opening month of the season but made just four further appearances during the first half of the season. On 20 February 2007, Blake made his first league start for the club in a match against West Bromwich Albion; Cardiff lost the match 1–0.