After returning from the Netherlands, Kingsbury worked in administration at
Victoria University of Wellington, rising to assistant registrar, before being appointed registrar of the newly created University of Waikato in 1964. He was influential in the development of Waikato, particularly in relation to the development of a school of Māori and Pacific studies and the responsibilities of the university towards Māori, the development of and access to continuing education and distance-learning programmes, and the founding of the Waikato Students' Union. He served as registrar for 24 years, until 1988. From 1978 to 1980, Kingsbury was registrar of the
University of Botswana. As chair of the New Zealand Tertiary Education Advisory Commission from 1988, he was a key figure in reforms to the tertiary education sector, and was regarded as the "father of the student loans scheme". In 1990, he was appointed as chief executive officer of the
New Zealand Qualifications Authority (NZQA). He retired from his roles with the Tertiary Education Commission and NZQA in 2000. ==Later life and death==