Nez, who enlisted in the Marines after the attack on Pearl Harbor, and 28 other Navajos were assembled by the Marines to transmit messages in their own language, developing a simple code that could not be understood by the Japanese military.
His family told KOAT-TV in Albuquerque of his death and said he was 93.
Nez spent his last years educating children and the public about the role played by the Code Talkers and published Code Talker: The First and Only Memoir by One of the Original Navajo Code Talkers of WWII in 2011. He used the signature Cpl. Chester Nez.
He told Indian Country Today Media Network in 2011 that at his boarding school the Navajo language was banned. He was proud that the once-forbidden tongue had helped the United States win World War II.
"The white man's military had accepted us as tough Marines. Hardened by the rigors of life on the reservation ... we often out-performed our white peers," Nez wrote of his wartime experience.
His wartime experience included the landing on Guadalcanal on November 4, 1942, the Battle of Bougainville in New Guinea on November 3, 1943, Guam on July 21, 1944, and Peleliu and Angaur in September 1944.
The Navajo Code Talkers -- the subject of a 2002 movie, Wind Talkers, starring Nicholas Cage and Adam Beach -- are the best-known of the Indian-language speakers used by the U.S. Military. But the tactic dates back to World War I, when the U.S. Army used Cherokee and Choctaw speakers to transmit messages in France.
During World War II, several hundred speakers of various tribal languages eventually worked in communications. The Marines also used Basque speakers early in the Pacific war, although the program was limited because Basques were known to be living in both Japan and the Philippines.