Robert Knowlton Smith (28 December 1887 – 26 October 1973) was a Conservative member of the House of Commons of Canada. He was born in Amherst, Nova Scotia and became a barrister. Smith studied at St. Francis Xavier University and the Dalhousie Law School where in 1911 he graduated with a Bachelor of Laws degree. He was mayor of Amherst, Nova Scotia in 1923, and served on that municipality's council for five years. In August 1925, he was designated a Crown Prosecutor for Cumberland County, but resigned that October to seek federal office.