He was educated at Te Aute College, where he was taught about modern theories of hygiene, promoted by James Pope, the Inspector of Native Schools. He came to believe that many aspects of Māori culture conflicted with health and hygiene. This view did not appeal to traditional Māori leaders.
In 1893 Pōmare left to study in the United States. He attended the American Medical Missionary College in Chicago, and graduated MD in 1899, returning to New Zealand the following year.
In 1900 there were fears of a bubonic plague, and the government addressed the problem of substandard hygiene and housing in the main centres and rural Māori settlements. Pōmare became Māori Medical Officer in 1901. District Māori Councils were also set up to prepare regulations on sanitation and hygiene. Pōmare travelled widely, inspecting water supplies and sanitary arrangements, and advising the Māori Councils. He became a skilled speaker when visiting Māori communities, which helped him break through the conservative attitudes of many older tribal leaders. He actively sought to remove the influence of tohunga (traditional healers), and supported the Tohunga Suppression Act of 1907. He believed assimilation into Pākehā society presented the best hope for the Māori people.
After 1907 the government lost interest in health reform and cut back funding for the Māori Councils. As a result the Councils stopped much of their work, and Pōmare was transferred to the Native Department.
In 1911 he was elected to Parliament representing Western Māori....