McCarthy was born in Beaumont, Texas, almost seven years after the discovery of oil at Spindletop. His father, Will McCarthy, worked in the oil fields and from the age of eight, the younger McCarthy served the roughnecks as a waterboy for 50 cents per day.^[2] During an oil drilling boom near Houston, Texas, the family moved to the city where his father gained employment. When he was 17, McCarthy enlisted in the U.S. Navy and returned to San Jacinto High School.^[1][3] He attended Tulane University on a football scholarship but injured his leg. He later attended Texas A&M University and Rice University, then dropped out of college and ventured into business.^[2] When he was 23, McCarthy married 16-year-old Faustine Lee, whose father William Lee was a partner in Yount-Lee Oil Company. McCarthy later claimed he had less than $1.50 to his name when he got married.^[4]

He talked his father and brother into working with him drilling for oil in Hardin County, Texas. The first attempt failed, but two years later, he made another attempt farther south near Anahuac, Texas and succeeded. Between 1931 and 1942, he struck oil 38 times.^[4] In 1941, McCarthy bought land where the future Astrodome was built along with 4,800 acres (19 km²) of what is now Sharpstown, Texas. During the 1940s, he established 11 oilfields and expanded several others.^[2]

"Diamond Glenn" drew much attention from the national media due to his charismatic personality and his rags-to-riches story. Both loved and scorned by the media, his image formed the cultural mythos of the Texas oil millionaire: a charming, lucky, unabashed businessman. In 1949, McCarthy built the luxurious Shamrock Hotel in Houston, spending $21 million for its construction. He then held what has been cited as "Houston's biggest party" for the hotel's grand opening.^[5] Dozens of Hollywood celebrities, many of whom were flown into Houston Municipal Airport on a Boeing 307 Stratoliner airplane which he had acquired from Howard Hughes.^[6]

Like most wildcatters, McCarthy was an aggressive investor. His multiple ventures led to a series of financial up and downs. In 1952, a life insurance company acquired the title to the Shamrock Hotel, which was sold to the Hilton Hotels Corporation.^[7] McCarthy restructured his business dealings and persisted. His business holdings included KXYZ radio station in Houston, two banks, a bar, a brand of bourbon called "Wildcatter", the McCarthy Chemical Company, a magazine, 14 "throwaway" newspapers and a movie production company known as Glenn McCarthy Productions.^[2] He served as chairman of the former Eastern Air Lines and president of the United States Petroleum Association.

McCarthy avoided publicity during his later career and lived with his wife in the La Porte area near Galveston, Texas. He had four daughters and one son, Glenn Jr. He died on December 26, 1988, one day after his 81st birthday, in Houston, Texas.^[8]

• George Bush Presidential Library and Museum 100 Tall Texans – Glenn McCarthy
• Glenn H. McCarthy - Great Citizens - 174 Years of Historic Houston (subscription required)
• Glenn McCarthy interview by Mike Wallace, July 21, 1957, utexas.edu; accessed December 25, 2016.
• McCarthy, Glenn and David Courwright. Glenn McCarthy Oral History, Houston Oral History Project, March 31, 1976.