Gao later joined the BJP and won the Arunachal East seat in the 2004 Lok Sabha election. He served as vice-chairman of the National Commission for Scheduled Tribes in 2003–04. After losing in 2009 and 2014, he regained the seat in 2019 and has also led the state BJP as its president.
In Parliament he is known for raising border issues with China; in February 2020 he told the Lok Sabha that several areas of Arunachal Pradesh were missing from official political maps. In the 2024 election he retained Arunachal East, defeating Congress candidate Bosiram Siram by 30,421 votes. He has since raised issues such as mobile connectivity in remote areas like Vijaynagar and discrimination faced by people from the Northeast.
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