He was the second son of Rev. Kinnear, the Presbyterian minister of Lower Clonanees, Dungannon, Co Tyrone. He was educated at the local elementary school but was refused admission to Dungannon Royal School because of his Presbyterian background. He was educated at Royal Belfast Academical Institution and, following his father into the ministry, he was ordained minister of First Letterkenny Presbyterian Church in 1849.
Rev. Kinnear was the first minister of the cloth to sit in the House of Commons and he was always dressed in clerical garb. In Parliament, he spoke on issues such as land reform and Temperance. A strong speaker and a defender of human rights, he faithfully represented Co. Donegal at Westminster for five years. Rev. Dr. Kinnear was a persistent advocate of a united education system. He was an early supporter of the Tenant Right Movement which sought Land Reform in Ireland. He successfully fought the 1880 Westminster election having support from all sections of the Donegal community.
A portrait of Rev. Dr. Kinnear hangs in the hallway at Monreagh Ulster Scots Heritage Centre. This life-sized portrait was presented to him to mark the occasion of his Ministerial Jubilee in September 1898.
Further reading: Letterkenny Historial Society