Admitted to the bar in 1911, he practiced law privately until he was appointed City Attorney for about a year.
During World War I, he served in the U. S. Army Air Service as a balloon pilot and attaining the rank of captain.
Mason returned to the U.S. military in World War II, where he served in the Air Force as a command pilot and attained the rank of colonel.
In 2014, Sig Ep, the journal for Sigma Phi Epsilon fraternity members reported that Charles W. Mason had died on January 18, 1969.
The obituary read: World War I and World War II Veteran, Oklahoma Supreme Court Chief Justice and VA Epsilon Brother Colonel Charles W. Mason, U.S. Army died on this date.