 The club previously tried to sign him the previous transfer window last year but he rejected the move to stay at Inverness CT.

Tansey made his Aberdeen debut on 13 July 2017 in a UEFA Europa League second qualifying round first leg at home to NK Široki Brijeg, starting in a 1–1 draw; and helped the side win 2–0 in the second leg.He then set up two goals in two matches between 12 August 2017 and 19 August 2017 against Ross County and Dundee.However, Tansey struggled to hold down a regular place in the Aberdeen team, as well as, competitions in the midfield.