He served in the United States Naval Reserve during World War II, from 1942 to 1945.

He was a member of the Pennsylvania Game Commission from 1948 to 1953, and was a Special Master for the Supreme Court of the United States from 1964 to 1972.

[2] On June 8, 1953, Willson was nominated by President Dwight D. Eisenhower to a seat on the United States District Court for the Western District of Pennsylvania vacated by Judge Owen McIntosh Burns.

Willson was confirmed by the United States Senate on July 14, 1953, and received his commission the same day.

He assumed senior status on October 18, 1968, serving in that capacity until his death on August 3, 1998, in Smethport.