[2] He previously played for Red Hurricanes Osaka in Japan, Glasgow Warriors in Scotland,[3] US Carcassonne in France and Miami Sharks in the United States.
Grigg was born and raised in New Zealand, but has represented Scotland – for which he is eligible due to his Scottish heritage – both in the fifteen-a-side form of the game and rugby sevens.
He graduated from the Scottish Rugby Academy and signed a professional contract with Glasgow Warriors on 23 March 2016.
[3] Grigg said that playing for Glasgow Warriors had much improved his life, although the move from New Zealand had been scary, and praised the players, the people and the culture.
[19] On 6 October 2022, it was announced that Grigg signed an injury replacement contract with French side US Carcassonne to play in the Pro D2, where he joined with fellow ex-Scotland international and ex-Glasgow Warrior Rob Harley.
[21] Grigg returned to Hawke's Bay for the 2023 season[22] and scored his first try for the province on 15 September 2023 in a 57–7 win over Manawatu.
[23] On 7 December 2023, the Miami Sharks announced the signing of Grigg ahead of their inaugural Major League Rugby season.
[25] On 13 February 2025, Grigg was named in the Old Glory DC squad for the 2025 Major League Rugby season.