John Douglas Guise was born on August 29, 1914, in Gedulalara Village near Dogura, Milne Bay Province. His parents, Edward Guise,  a mission worker, and Grace Neliada Samoa, married on May 7, 1913.

He only had four years of formal education and at the age of 14, he began working on Samarai Island as a waterside worker for Burns Philp which was the first company to offer tourism in New Guinea in the 1880s.

He joined the Australian New Guinea Administrative Unit (ANGAU) as a clerk in Signals and then in 1946 he joined the Police Force after World War 2, rising to the rank of Sergeant-Major. He spent the next five years in the Department of District Services in Port Moresby.

In 1958, he was appointed president of the Port Moresby Mixed Race Association, marking the beginning of his political journey. Both of his parents were of mixed European and Papuan descent, placing him within a community that often struggled for recognition. During the 1950s and 1960s, the association played a significant role in Papua New Guinea by uniting people of mixed heritage to advocate for their rights and assert their identity in a society that regarded them as neither fully “native” nor “non-native.”

Sir John Guise was the first Papua New Guinean to be honoured with an honorary doctorate of law from the University of Papua New Guinea. In 1961, Guise entered the legislative council as a member for East Papua and he was described as the most successful early Indigenous politician at that time. 

In 1967, Guise led the committee on constitutional development and supported a presidential system of government, though a version of the Westminster system was later chosen instead. In 1968, he became Papua New Guinea’s first local Speaker of the House of Assembly. By 1972, he was Deputy Chief Minister under Michael Somare and backed Somare’s push for self-government, independence, and a multi-racial society. He was knighted in 1975 when he became the first Governor-General of Papua New Guinea upon PNG gaining independence. 

Guise believed the governor-general should act as a guardian of the Constitution and the people’s rights, not merely follow the example of the Australian Governor-General or serve as a symbolic figure. He made this clear in a 1975 statement quoted by Australian journalist Keith Jackson.

He resigned from his vice-regal position in 1977 at the age of 63 and returned to politics. He was for a time the deputy opposition leader and remained in Parliament until 1982. After retiring from politics, he stayed active in public life – helping guide the University of Papua New Guinea as a council member, overseeing the Copra Marketing Board as its chairman, and sharing his views through a weekly column in the Times of Papua New Guinea.

Sir John Guise was married to Mary Miller. They had two sons. However, she sadly died in 1944. Guise then remarried in 1947 to Unuba Aukai from Lalaura in the Central Province, and they went on to have seven children.

Sir John Guise was described as a father of inspiration to many leaders in PNG. He was the man who addressed the nation as PNG’s first Governor General when the clock struck midnight, and the date changed from 15th September to 16th September 1975, the day PNG gained its independence.