Coke was born in Williamsburg, Virginia to John and Eliza (Hankins) Coke. He graduated from the College of William and Mary in 1848 with a law degree. In 1850 he moved to Texas and opened a law practice in Waco. In 1852 he married Mary Horne of Waco. The couple would have four children, but all of them died before age 30.

Coke was a delegate to the Secession Convention at Austin in 1861. In 1862 he raised a company that became part of the 15th Texas Infantry, and served as its Captain for the rest of the war. He was wounded in an action known as Bayou Bourbeau on November 3, 1863 near Opelousas, Louisiana. After the war he returned home to Waco.

In 1865 he was appointed a Texas District Court judge, then in 1866 he was elected as an associate justice to the Texas Supreme Court. The following year the military governor, Philip Sheridan, ordered his removal as a part of the Reconstruction policies.

Coke was elected governor as a Democrat in 1873 and took office in January of 1874. His administration was marked by vigorous action to balance the budget and by a revised state constitution adopted in 1876. He was also instrumental in creating the Agricultural and Mechanical College of Texas, which became Texas A&M University.

The governor resigned his office in December of 1876 following his election to the United States Senate. He would be elected to that office twice more, serving until March 3, 1895. Coke was not a candidate for reelection in 1894.

He retired to his home in Waco and his nearby farm. He became ill after suffering exposure while fighting a flood of the Brazos River in April of 1897. After a short illness, he died at his home in Waco on May 14, 1897 and was buried in the Oakwood Cemetery there. Coke County is named in his honor.