Allen attended Hastings Boys' High School and played 1st XV rugby for the school, alongside his identical twin brother, Reuben Allen. Since finishing his secondary school education, he has played premier club rugby for Havelock North Rugby Club.[3]
Allen represented Hawke's Bay at age grade level, including the Hawke's Bay U18 team in 2022 and the U19 team in 2023,[3][4] and was part of the Hawke's Bay Academy.[5]
In September 2022, Allen was selected in the Hurricanes U18 squad for a Super Rugby Development Camp.[6] Half a year later, he was named in the Hurricanes U20 team for the Super Rugby U20 competition in Taupō.[7] The Hurricanes U20s finished the 2023 tournament in second place.[8]
Senior career
At only 19 years old, Allen was named in the Hawke's Bay squad for the 2023 Bunnings NPC season.[9] He made his debut for the Magpies on 16 August 2023 against Waikato.[10] That was his only game for the province in two seasons. He was again named in the squad for 2024,[1] but didn't get any game time that season.
In March 2024, he was for the second year named in the Hurricanes U20 squad for the Super Rugby U20s tournament.[11] The team ended the 2024 tournament in third place.[12]
Prior to and during the 2024 Super Rugby Pacific season, Allen trained with the Hurricanes while on a National Development Contract. On 27 June 2024, the Hurricanes announced that the franchise had signed Allen until the end of 2026 on a full contract.[2]
International career
On 7 October 2022, Allen was named in the New Zealand Schools squad for two matches – against the NZ Māori U18 team and Fiji Schools – to be played at a New Zealand Under 18 Quadrangular Tournament in Hamilton.[13]