Having helped Cardiff reach the final of the League Cup, Mason scored the first goal against Liverpool at Wembley Stadium on 26 February. With the score level after 90 minutes, Mason was substituted for Filip Kiss. Cardiff lost 3–2 on penalties after the game finished two-all. Mason scored his 9th and 10th goals against fellow play-off hopefuls Brighton and Middlesbrough respectively, which put him in the top three goal scorers at Cardiff. On 20 April, Mason signed a new contract to extend his stay in the Welsh capital until the summer of 2016. He celebrated his contract extension with a goal against Leeds United, then later on Mason was awarded the Club Young Player of the Year award. He enjoyed a really impressive first season in the Welsh Capital having scored 12 goals, more than he scored in his previous two put together and Cardiff had reached the play-offs but were however knocked out by West Ham United in the semi-finals.