He made his Brumbies debut during the 2012 Super Rugby season against the Sharks in Canberra.

[citation needed] Sio was named in the Wallabies 31-man Squad to take on the British and Irish Lions in their three test series.

[citation needed] Sio made his run-on debut at loosehead prop against the All Blacks during the winning final of the 2015 Rugby Championship, after a pair of impressive cameos from the reserves bench against South Africa and Argentina.

[citation needed] He is son of the former Samoan prop David Sio, who played in the 1991 Rugby World Cup (Samoa played against Scotland in that tournament at the time of Scott's birth and he was named in recognition of the occasion)[3] and also the cousin of up and coming player Fereti Sa'aga who has also represented Australia on the Junior stage.

On 17 August 2022, Sio would travel to England to join Exeter Chiefs in the Premiership Rugby on a long-term deal from the 2022-23 season.