He joined Heriot's Rugby Club for the 2013/2014 season, winning the Scottish Cup after beating Glasgow Hawks RFC 31-10 in the final at Broadwood Stadium.

Douglas gained a professional contract with the Melbourne Rebels for the 2017 Super rugby season after impressing whilst on a trial during pre-season training.

[13] Upon the conclusion of the 2018 Mitre 10 Cup season, Douglas accepted a two-year contract with Canberra based Super Rugby franchise ACT Brumbies.

[15] Douglas played in the ACT Brumbies 28-23 victory over the Queensland Reds in the Super Rugby AU final at GIO Stadium on 19 September 2020.

[18] Douglas signed a two-year contract with Japanese club Yamaha Jubilo ahead of 2021 Top League season.