[1] In 2004, he was elected to the 4th Arunachal Pradesh Legislative Assembly from Liromoba constituency in West Siang district and became the Home Minister in the Gegong Apang led government.

He was instrumental in toppling the Apang ministry and installation of Dorjee Khandu as the chief minister in April 2007.

[2] In 2009 he was re-elected to the 5th Arunachal Pradesh Legislative Assembly from the same constituency and became the Power Minister in the Dorjee Khandu led state cabinet[4] on 6 November 2009.

On 5 May 2011, Gamlin became the Chief Minister of Arunachal Pradesh after the death of Dorjee Khandu on 30 April 2011.

[9] Thousands including President Pranab Mukherjee, and Prime Minister Narendra Modi paid their respects.