Oliver H. P. Garrett was born on March 6, 1894 in New Bedford, Massachusetts to Legh Osborn and Alice Palmer Garrett. His father was an efficiency expert who passed away in 1899. His mother once operated a business that imported goods from India and the Far East and served with the YMCA in France during the First World War.

Garrett worked on newspapers in Boston and New York and wrote stories for magazines before coming to Hollywood in 1927. He would later share an Oscar with Joseph L. Mankiewicz for best screenplay for Manhattan Melodrama (1934) and became a founding member and two term vice president of the Screen Writers Guild.

On February 22, 1952, whilst visiting New York City, Garrett suffered fatal heart during a shopping trip. He was survived by his wife and three sons.