Pairin began his active political career in 1975. He was elected a Member of the Sabah Legislative Assembly for the Tambunan electorate in 1976 under the Sabah People's United Front party ticket, a party which was led by Harris Salleh and was appointed as a Minister in the cabinet of the ruling party. Tambunan has become his stronghold ever since. Over time, Pairin became disillusioned with the party's leadership, and opposed some of the party's policies. He felt that the party had deviated from its original struggle. He however, remained firm with the party and subsequently, he was forced to leave the ruling party coalition in 1984.
Election results
Leadership
In December 1984, he challenged as an Independent candidate against the ruling party to defend his seat in the Tambunan by-election. His leadership in a state within a federation which had the official religion of Islam, was also questioned because of his religion. Pairin easily won and defended his seat with significant majority. In March 1985, Pairin formed Parti Bersatu Sabah. Despite overwhelming odds, he succeeded in registering PBS as a political party in the eleventh hour; thus paving the way for the party to contest against the incumbent state government in the 1985 Sabah state election in April. PBS won a majority of 25 out of the 48 seats contested in the 1985 state elections. However, BERJAYA and the United Sabah National Organisation joined forces submit their candidate as the chief minister, but after riots by BN followers, the newly formed coalition between BERJAYA and USNO was dissolved giving PBS the majority government. Pairin was sworn in as the seventh Chief Minister of the state of Sabah. He held the post of Sabah Chief Minister from April 1985 to March 1994, during which he spearheaded his party's triumphant outings in four successive state elections. In the 1994 state election, PBS won the election, however shortly after being announced the winner, almost all PBS assemblymen defected to Barisan Nasional. Pairin was not allowed to be sworn in as Chief Minister. Tun Sakaran Dandai of UMNO was then sworn to be the eighth Chief Minister of Sabah. On 6 June 2015, Pairin asserted a "clear connection of the incident to the 2015 Sabah earthquake that has brought about so much damage and loss of lives" by a group of European nude tourists on Mount Kinabalu Pairin is also the Huguan Siou or Paramount Leader of the Kadazan-Dusun community for being the President of the Kadazandusun Cultural Association, the community's principal cultural association. However, there is a growing concern that Pairin is no longer suitable to hold the Huguan Siou title and that he should give way to the younger generation.
