Pembleton graduated high school in Stamford, Connecticut in 1907. He studied design and drawing in New York in the 1910s and undertook "extension work in architecture" at Columbia University from 1918 to 1920 while working for A. C. Bossom as a designer and specification writer. In 1921 he became chief designer for the U. S. Government in Puerto Rico, then in 1922 took a job as a partner in the firm of G. Gadsden Sayre in Greensboro, North Carolina.
In 1927 he began working for the Birmingham firm of Miller and Martin as a chief draftsman for commercial projects. From 1935 to 1938 her worked for the Federal Housing Administration in Birmingham as a staff architect. He applied for professional registration in Alabama in 1936 and opened his own practice two years later.
Pembleton brought his experience with the federal housing program to his private practice, which came to specialize in public housing developments. He was joined by Edgar Mims in 1945 and retired from active practice in 1951. He died ten years later.
- Schnorrenberg, John M. (June 1992) "Harry Pembleton; Pembleton and Mims; Mims, Gaunt, and Poole; Mims and Gaunt: Perspective Renderings of Works from an Architectural Practice, 1938-1992." exhibition catalog. Birmingham Public Library