Koi Oboadabang Larbi was a Ghanaian barrister and judge. He was a justice of the Supreme Court of Ghana from 1970 to 1972.

Koi Larbi was born in 1914 in Gold Coast. He obtained his law degree in 1943 from Durham University working at the West Indian seamen hostel as the warden. While in school, he was a member of the West African Students Union (WASU).

He qualified as a barrister at the Middle Temple in January 1944 and began private practice in London.

He became a legal advisor to the Gold Coast Farmers' delegation in the United Kingdom in 1945, and the following year, he became a legal advisor to the West African National Secretariat (WANS).

He was also a member African Progress Association and the chairman of the Committee for the Defence of People of African Descent, a committee that was formed to provide legal support to Black people.

Koi Larbi returned to the Gold Coast to resume private legal practice. He was called to the Gold Coast bar in 1946. In 1969 he was appointed member of the Council of State[10] and a year later, he was appointed Justice of the Supreme Court of Ghana on 5 August. He was dismissed in 1972 when the Supreme Court was abolished by the National Redemption Council.