Julius W. Blackwell was an American politician and a member of the United States House of Representatives that represented fourth and third districts of Tennessee in the United States House of Representatives. He was born in Virginia in 1797 and attended the public schools. He moved to Tennessee and settled in Athens, McMinn County. He was elected as a Democrat by the fourth district to the Twenty-sixth Congress, which lasted from March 4, 1839 to March 3, 1841. He was an unsuccessful candidate for re-election to the Twenty-seventh Congress in 1840.

After the number of electoral districts Tennessee held had been reduced and reapportioned, he was elected by Tennessee's third district to the Twenty-eighth Congress, which lasted from March 4, 1843 to March 3, 1845. He was an unsuccessful candidate for re-election to the Twenty-ninth Congress in 1844.