In 1877 he was admitted to the bar in Daingerfield, Texas, and commenced practice in Jefferson, later moving to Dallas in 1887.

[2][3] Culberson's political career began with his election as Attorney General of Texas in 1890, a position he held until 1895, after campaigning for and winning the governor's race in November 1894.

Culberson was opposed to demands for racial equality, stating that efforts to do so would lead to the "consequent debasement, degradation or destruction of the white race".

However, his health and opposition to the Ku Klux Klan finally led to the loss of his seat in the Democratic primary in 1922.

[1][5] He was succeeded by fellow Democrat Earle Bradford Mayfield, the outgoing member of the Texas Railroad Commission.