Wilson was born to Will R. and Kate Wilson in Dallas, where he graduated from Highland Park High School. He received his bachelor of science degree in geology at the University of Oklahoma at Norman. Then he entered the law school of Southern Methodist University in Dallas, where he was named a "Distinguished Graduate". He joined the law firm of Turner, Rogers, and Wynn and served as aide to Dallas Mayor Woodall Rogers, who served in the nonpartisan position from 1939-1947. Wilson left Dallas to become an assistant Texas attorney general in the state capital in Austin.

During World War II, Wilson joined the United States Army and advanced to the rank of major, having served in New Guinea and the Philippines, where he was on the staff of general Walter Kruger and I.P. Swift. He was the battalion commander of the 465th Field Artillery. He accepted the surrender of the staff of the Japanese General Yamashita and received the Bronze Star for heroism in combat from General Swift. After the war, Wilson returned to Dallas to practice law.

In 1946, he was elected to a four-year term as district attorney of Dallas County, having served from 1947 to 1951. In 1950, he was elected to the nine-member Texas Supreme Court, the final authority in civil cases and juvenile matters in the state. He left the court as associate justice in 1956 to run for attorney general to succeed John Ben Shepperd.

While he was attorney general, he received the Wymann Memorial Award for 1959—1960 as the "Outstanding Attorney General in the United States." He moved to halt prostitution in several cities, including Galveston, Victoria, Cuero, Big Spring, Texarkana, Beaumont, and Port Arthur. Wilson's service as the top lawyer for state government ended in January 1963, when he was succeeded by fellow Democrat Waggoner Carr of Lubbock.

In the spring of 1961, Wilson, along with some seventy other individuals, paid the $50 filing fee to enter the special election for the U.S. Senate seat vacated by Vice President of the United States Lyndon Baines Johnson, who along with John B. Connally, Jr., as U.S. Secretary of the Navy, had joined the new administration of John F. Kennedy. Wilson trailed in fourth place in the special election with 121,961 votes (11.5 percent). Ultimately, Republican John G. Tower, a college professor from Wichita Falls, won the remaining five and one-half years of Johnson's term by approximately ten thousand votes over Senator William Blakley of Dallas. who had been appointed on an interim basis by Governor Daniel, himself a former U.S. senator and Texas attorney general.

Wilson did not seek a fourth two-year term as attorney general in 1962; instead he entered the Democratic gubernatorial primary against several prominent opponents, including incumbent Governor Marion Price Daniel, Sr. of Liberty, highway commissioner Marshall Formby of Plainview, General Edwin A. Walker, who made anticommunism the centerpiece of his campaign, and the leading candidates, former U.S. Secretary of the Navy John Connally of Floresville, and liberal attorney Don Yarborough of Houston (no relation to his fellow liberal U.S. Senator Ralph W. Yarborough of Austin). In the campaign, Wilson was particularly critical of a politician not on the ballot: Lyndon Johnson. Wilson declared that Johnson had engineered Connally's candidacy because the vice president feared a Republican victory in Texas in 1962. According to Wilson, Johnson was engaged in "a move . . . to oust Price Daniel, oust me, oust Senator Ralph Yarborough and gain complete control of the state government."

Ultimately, Connally narrowly won the nomination in a runoff against Yarborough and then defeated the strong Republican gubernatorial candidate in Texas since 1924, Jack Cox of Houston in the general election. Cox had lost the Democratic nomination to Governor Daniel in the 1960 party primary. In 1964, Cox, a part of the conservative wing of his new party, lost the Republican nomination for the U.S. Senate to George Herbert Walker Bush, also of Houston, and the future vice president and U.S. president.

After his Senate and gubernatorial election defeats, Wilson co-founded the law firm, Wilson, Kendall, Koch, and Randall in Austin. He served from 1969-1971 as the assistant attorney general in charge of the Criminal Division of the Justice Department. Wilson's book A Fool For a Client focuses upon President Nixon's decline, pending impeachment, and ultimate resignation from the Oval Office. The conservative Wilson switched to the Republican Party more than five years before Connally. Ironically, it was Connally, considered a political pragmatist, whom Nixon most highly regarded, having appointed him U.S. Secretary of the Treasury in 1970 and reportedly having considered Connally for the vice-presidential nomination vacated in 1973 by Spiro T. Agnew.

Wilson was married for thirty-six years, until her death, to the former Marjorie Lou Ashcroft (1918—1984). The couple had two children and five grandchildren. Known for his cowboy humor, Wilson operated two ranches: Brushy Creek in Williamson County and Little River Ranch in Milam County. He served as director of the Brushy Creek and Upper Brushy Creek Water Control Improvement Districts for two decades. He was also chairman of the Cullum and Boren and the Wilson Land and Cattle companies.

Wilson died at the age of ninety-three and was interred on December 17, 2005, alongside his wife in the Patriot's Hill section, Row R, No. 24, of the Texas State Cemetery in Austin.