From 1873 – 1878, Metcalfe was Alderman for Frontenac Ward in Kingston. In 1879, he became a member of the Provincial Parliament of Ontario. After the death of Sir John A. Macdonald in 1891, he succeeded him as member for Kingston in the Federal parliament.

Metcalfe was Warden of Kingston Penitentiary from May 22nd 1896 to May 17th 1899. Metcalfe became warden during the sitting of a Royal Commission into penitentiary management. Metcalfe, new to the prison, depended on the new deputy warden, Daniel O’Leary, and Chief Keeper William St. Pierre Hughes (later the superintendent of penitentiaries), to guide his actions. He spent much of his time reorganizing the prison’s departments in accordance with the Royal Commission’s wishes. Metcalfe fell ill in late 1898, and the Accountant of Penitentiaries, George Foster, acted as Warden. Metcalfe was bedridden in Cedarhedge for much of 1899 until he retired.

It was said of Metcalfe that he had “the suavity of a Laurier, the magnetic personality of a Macdonald, the volubility of a Tupper and the rhetoric of Cartwright…”.(Weekly British Whig, Jan. 5, 1925). He died in Kingston on January 1, 1925, predeceased by his wife and five of his eleven children.