Joseph Wellington Byrns Jr. (August 15, 1903 – March 8, 1973) was an American attorney and one-term U.S. Representative from Tennessee.

In 1938, Byrns won the Democratic nomination for his father's old House seat and was elected to that office in November of that year.

His vote for an amendment that would have postponed the operation of the Selective Service Act by 60 days helped to inspire opposition from an independent candidate named Percy Priest, who was a member of the editorial staff of the Nashville Tennessean.

Byrns served on active duty in the United States Army during World War II, from June 23, 1942 until August 17, 1945, almost all of this time in the European Theater of Operations.

Byrns died in Daytona Beach, Florida on March 8, 1973, aged 69, and is interred at Mount Olivet Cemetery in Nashville along with his parents and second wife.