 He started off the 2015/16 pre season in good form, scoring against Harrogate Town on 10 July 2015, and then scoring against Eintracht Frankfurt in a 2–1 defeat on 21 July 2015.On 31 July 2015, Morison was given the number 20 shirt for the upcoming 2015/16 season.On 4 August 2015, Morison rejoined League One club Millwall for a third spell, for an undisclosed fee.