After starting practice with his father, the young man established his own office in Rochester in 1881, and during a long and successful career he participated in civic matteres, serving as Chairman of the City Planning Commission during one period.
With an office in the Grant Building in Rochester, Mr. Warner was active in practice, and under his own name designed a number of public and business structures, among them the Monroe County Court House, one of his early commissions; Powers Hotel; Mechanics Institute; Telephone Building; Mercantile Building; Orphans' Home, and the Granite Building. In addition he served as architect of the Ford Hotels built in Rochester, Erie, Buffalo, and at Toronto and Montreal in Canada, also served as Supervising Architect on erection of the Hospital for the Insane at Utica. During a later period Mr. Warner was associated with the New York firm of McKim, Mead & White in designing the Lincoln Alliance Building in Rochester, the Rochester Savings Bank and its various branch buildings.
He was an active member of the Central New York Chapter.