In his debut season, Alston finished as the club's joint top goalscorer, along with Ron Futcher, in the league as the club suffered relegation. However, Alston spent just one season at Kenilworth Road as the club began to experience financial difficulties resulting in Alston not being paid at times. Alston later described his decision to reject offers from Germany and return to England with Luton as "the biggest mistake I ever made". Cardiff City manager Jimmy Andrews paid £20,000 to take him to Ninian Park with the club also agreeing to pay Alston the wages owed to him by Luton. He scored twice on his debut in a 4–3 win over Chesterfield and later went on to become the first post-war Cardiff player to score a hat-trick in the FA Cup in a 6–2 win over Exeter City. In his first season, the club won the Welsh Cup, qualifying for the European Cup Winners' Cup the following season. In the first round of the competition, Alston became the first Australian player to score in a European competition when he scored in a 1–0 victory over Georgian side Dinamo Tbilisi on 15 September 1976.