Aitken played for amateur sides Kirkintilloch and Queen's Park, before joining Rangers for the 1918–19 season. He scored two goals in 21 league games as they finished second to Old Firm rivals Celtic in the Scottish League Division One. Aitken then left Ibrox Park for England to play for Port Vale in the summer of 1919. He scored on his debut at inside-right in a 2–0 win at Aston Villa Reserves in a Central League match on 20 August 1919. After Vale were elected to the Football League Second Division in October 1919, the Vale were forced to pay £500 to Rangers for his and Peter Pursell services. He scored nine goals in 44 games in 1919–20, and was in the cup winning sides of 1920. He was sold on to Newcastle United for £2,500 in May 1920, which was considered a bargain at the time. He began playing as an inside-forward at St James' Park, and although he only scored ten goals in 110 league games in four seasons at the club, his unselfishness in attack and overall contribution to the team was greatly appreciated. Newcastle finished fifth in the First Division in 1920–21, with Aitken claiming three goals in 38 appearances. He was limited to 16 games as United finished seventh in 1921–22. They then finished fourth in 1922–23, with Aitken scoring four goals in 26 matches. He scored three goals in 30 appearances as Newcastle posted a ninth-place finish in 1923–24. He played alongside Stan Seymour and Tommy McDonald. In 1924 Aitken signed for Preston North End for £1,000. He then joined Chorley, Norwich City, and Bideford Town. He travelled to Italy, and impressed Juventus chairman Edoardo Agnelli with his idea of exporting the playing system pioneered by Arsenal manager Herbert Chapman. However, not everyone was convinced by his new methods, and some "Juve" players were unwilling to put in the extra work required to make the system work. He nevertheless led the "Old Lady" to a third-place finish in 1929–30. Though he found little success at Stadio di Corso Marsiglia, his methods were built upon by future coaches at the club. He was unable to take to the field as player, as foreigners were not permitted to play in the Italian leagues. He eventually ended up playing and coaching football in France for AS Cannes, Stade de Reims and FC Antibes. At Cannes he was part of the team that reached the Coupe de France final at the Stade Olympique Yves-du-Manoir on 24 April 1932, which they won 1–0 over RC Roubaix. They also finished as runners-up in the Ligue de Football Professionnel in 1932–33. With Stade Reims, he won the Championnat de France amateur league in 1935.
Later career
He returned to Britain during World War II, and worked as a defence contractor at Vickers-Armstrongs. He later coached in Belgium and Norway, and became a representative of a wine and spirits distributor in Tyne and Wear.
