Horatio was the fourth son of Alfred and Caroline Boultbee.  He was born June 24, 1866 at Newmarket, Canada West.  He was a graduate of the University of Toronto University of Toronto, and of Osgoode Hall Law School Osgoode Hall Law School.
 He was an ardent tennis player and was the founder of the Toronto Lawn Tennis Club Toronto Lawn Tennis Club.  In 1890 and 1891, he was articled with his father's firm of Boultbee & Boultbee Boultbee & Boultbee.  In 1892, he was a partner with the firm, and stayed until his father's death in 1902.  For a few years he practised law alone, but in 1909, Boultbee:Horatio Clarence Horatio and his older brother Boultbee:Alfred Ernest (Pet) Alfred switched to their second profession, architecture, and together they were responsible for the subdivision, development, winding streets and colonial type of homes in southern Rosedale development, Toronto Rosedale, still a fine residential area of Toronto.  Horatio's home in Rosedale at 35 Crescent Road has been declared an Historical home of Horatio Clarence Boultbee historical home that must be preserved.
 Keenly interested in literature, music, drama and art, Horatio was the author of two books of poems entitled The Oxford Lists and other poems The Oxford Lists and other poems, and The famous men of England and last poems The famous men of England and last poems.

 Horatio Boultbee died in 1951.