In 1914, he ran for Pauls Valley city attorney and won the position.
In 1932, he ran for his first statewide office and in 1934 he won the race for Attorney General for the State of Oklahoma.
[2] His 25 years in office are the longest of any Oklahoma Attorney General.
Williamson died at age 75 on October 15, 1964, at his home in Oklahoma City.
[3] He was buried in Mount Olivet Cemetery in Pauls Valley.