Born on the island of Hawaii, Nāwahī received his formal education in the Protestant missionary schools of the islands. He began his career as a teacher at the Hilo Boarding School and later became a self-taught lawyer. He was also an accomplished artist, and was one of the few indigenous Hawaiian painters to work in Western styles during the 19th century. Entering the realm of politics in 1872 as a member of the House of Representatives, he represented his home districts of Puna and later Hilo in the Legislature of the Kingdom of Hawaii for two decades. Serving in the final legislative assembly 1892–1893, he became a political leader for the Liberal faction in the government. He established himself as a leader in the opposition to the unpopular Bayonet Constitution of 1887 and as a defender of the idea of Hawaiian nationhood and self-rule. Alongside William Pūnohu White, he was a principal author of the proposed 1893 Constitution with Queen Liliʻuokalani. They were decorated Knight Commanders of the Royal Order of Kalākaua for their service and contribution to the monarchy. Three days after an attempted promulgation of the constitution, the queen was deposed in a coup during the overthrow of the Kingdom of Hawaii on January17, 1893.