John Twiggs Myers was born on January 29, 1871, in Wiesbaden, Stadtkreis Wiesbaden, Hessen, Germany. He was the son of Abraham Charles Myers and Marion Isabelle Twiggs Myers. He was the husband of Alice Gertrude Cutts Myers.

After graduating from the United States Naval Academy in 1892, he was commissioned a Second Lieutenant in the United States Marine Corps in 1895. He participated in actions during the Spanish-American War (1898), the Philippine Insurrection (1899), and Boxer Rebellion (1900), and would later lead expeditions to the Philippines (1906-1907), Santo Domingo (1912), and Cuba (1913). Promoted to Brigadier General in 1929 and to Major General in 1931, he commanded the Marine Department of the Pacific from 1933 until his retirement in 1935. During World War II, he was promoted to Lieutenant General (1942).