Following his secondary schooling at Te Aroha College, Trevor completed his Diploma in Physical Education at Otago in 1973 and a Diploma in Teaching from Auckland Secondary Teachers College. He later completed a Master of Science in Recreation Administration with Honors at Indiana University and a Master of Public Policy from Victoria University of Wellington.
Trevor Garrett has had an outstanding career in the state sector over many years. He initially occupied senior roles in the Department of Internal Affairs, including Chief Executive of Recreation and Development, and had oversight of the New Zealand Lottery Grants Board, gaming, racing, passports, citizenship and censorship. He was accepted for, and completed, the Senior Manager in Government Program, John F. Kennedy School of Government, Harvard University.
Trevor was Chief Executive of the Casino Control Authority, which he established on behalf of the government and led for 13 years, before being appointed to his current position as Chief Executive of the Charities Commission in 2005. He was also President of the New Zealand Association of Health, Physical Education and Recreation for two terms, a member of the National Executive for 13 years, and in 1990 received a Commemoration Medal for Services to New Zealand.