He was born the only child of Henry Lewis and Sarah Lawes (née Abbott). His father worked as a prison guard at the New York State Reformatory, now called the Elmira Correctional Facility.
Lewis Lawes ran away at 17 and joined the United States Coast Artillery. Afterwards, he worked at an insurance company, before beginning his prison career as a guard at Clinton Prison in Dannemora, New York on March 1, 1905. On September 30, 1905, he married Katherine Stanley. He subsequently worked at first Auburn Prison, then Elmira Reformatory. In March 1915, he was named Superintendent of the City Reformatory on Hart Island in New York City. In 1918, Lawes became warden of the Massachusetts State Prison. New York Governor Al Smith asked him to take over Sing Sing, a notorious prison where wardens seldom lasted very long. On January 1, 1920, Lawes took charge. He was to remain at his post for twenty-one years, instituting reforms, until he retired in 1941.
Lawes became the president of the Boy Rangers of America in 1941.
Lawes wrote several books. Several of his works were made into films. His most famous book, Twenty Thousand Years in Sing Sing, was made into a 1932 movie under the same title, starring Spencer Tracy, and again in 1940 as Castle on the Hudson, featuring John Garfield. Invisible Stripes (1939), with George Raft, was based on his novel of the same name, while Humphrey Bogart starred in You Can't Get Away with Murder (1939), an adaptation of Chalked Out, a play he co-wrote.