Tuiono was born on 25 December 1972.[2] He is both Cook Islands Māori (Atiu) and New Zealand Māori (Ngāpuhi and Ngāi Takoto); he is tangata whenua, and also belongs to the Pasifika/Moananui diaspora.[3][4] Tuiono grew up in Te Atatū and Ōtāhuhu, with a two-year period in Rarotonga. He initially enrolled for an engineering certificate but partway through changed to a BA in Māori Studies at the University of Auckland. He credits an environmental paper he took there, taught by Jeanette Fitzsimons, as turning him into environmental activism.[2] He followed his BA with a law degree, also from the University of Auckland.[5]
By profession, Tuiono is an education consultant who has previously worked at both the United Nations and was the activist in residence at Massey University.[6]
Tuiono stood for the Green Party at the 2017 election and was 16th on the party list. This was not high enough for Tuiono to be elected to parliament, as the party won only 8 seats.[6]
During the 2020 general election, Tuiono stood as the 8th ranked list candidate for the Green Party and as the party's candidate for Palmerston North. He came third place in Palmerston North, with 2,039 votes.[12] With the Greens winning 10 seats, he became a list Member of Parliament.[13][14] Tuiono is the Green Party's first Pasifika MP.[13]
During his campaign, Tuiono pledged to tackle wealth inequality in New Zealand.[15]
In late November 2023, Tuiono assumed the Green Party's Pacific Region, education, workplace relations and safety, space, national security and intelligence, and overseas development assistance spokesperson portfolios.[17]
On 7 December 2023, Tuiono was appointed as the third assistant speaker, the first Green Party MP to become a member on the speaker team[18] and the second MP, after Peter Hilt in 1996, from a party other than National or Labour to become an assistant speaker.[19]
On 10 April 2024, Tuiono's member's bill "Restoring Citizenship Removed by Citizenship (Western Samoa) Act 1982 Bill" passed its first reading with the support of the opposition Green, Labour, Te Pāti Māori and the government coalition parties ACT and New Zealand First. The bill proposes restoring citizenship eligibility to a group of older Samoans born between 1924 and 1949 when Samoa was still a New Zealand mandate territory.[20]
In December 2020, Tuiono joined fellow Green MP Golriz Ghahraman and LabourMPIbrahim Omer in pledging to form a new parliamentary Palestine friendship group to "raise the voices of Palestinian peoples in the New Zealand Parliament" during an event organised by the Wellington Palestine advocacy group to mark the International Day of Solidarity with the Palestinian people.[21]
Tuiono serves as his party's agriculture spokesperson. He supports regenerative agriculture and a move away from intensive dairy farming.
He considers it appropriate for MPs to be able to pledge allegiance to Te Tiriti O Waitangi instead of to the King.[22]