She has worked in Samoa as a Specialist Public Health Physician, has worked as a consultant for the World Health Organization in the Philippines, China, Cambodia, Vietnam, the Solomon Islands and Kiribati. She has worked for UNICEF in Fiji and the Secretariat of the Pacific Community in Samoa, New Caledonia and Fiji. In 2013 she completed the Global Health Delivery Summer Intensive Program at Harvard University and attended the Women's Leadership Summit at Harvard in 2019. 

Dr Sinclair currently works at Counties Manukau District Health Board in the population health team. Her role includes evaluation, health literacy and Pacific health.