Before entering politics, Ririnui worked for a number of notable Maori community organisations including Te Puni Kōkiri, and he is a registered minister of the Rātana church.

However, in the 2005 election, he lost his electorate seat to Te Ururoa Flavell of the Māori Party and remained in Parliament as a list MP.

In December 2004 Ririnui instead became a Minister outside Cabinet, as a Minister of State with Associate Ministerial roles in the Corrections, Health, Treaty of Waitangi Negotiations, and Forestry portfolios, and held these roles until the defeat of the Labour government in 2008.

Labour was defeated in the 2008 general election, meaning that Ririnui was unable to retain his ministerial positions.

In the case of Ririnui, he was accused of purchasing items such as golf clubs and a bike which violate the rules regarding the usage of ministerial credit cards.