Tirikatene-Sullivan was first elected to Parliament in the Southern Maori by-election of 1967, which was prompted by the death of the long-serving incumbent—her father Sir Eruera Tirikatene. Between 1972 and 1975 she was the Minister of Tourism. In addition she was Associate minister of Social Welfare from 1972 to 1974. She was Minister for the Environment from 1974 to 1975. She was re-elected by substantial majorities until the 1996 election, when the Southern Maori electorate was abolished in the transition to MMP. Tirikatene-Sullivan then contested the new Te Tai Tonga electorate, which covered much of the same territory as the old Southern Maori electorate, but she was narrowly defeated by Tu Wyllie of New Zealand First. She subsequently retired from politics.