Mercy Dee Walton was born in Waco, Texas, United States, he moved to California just before World War II. He started playing piano at age 13 and learned his style from many of the ten-cent party house pianists that played out in the country on weekends.

To make ends meet, he had to earn his living in the fields chopping cotton, picking grapes or cutting spinach. During this time, the musician who impressed Walton the most was Delois Maxey, who never had an opportunity to record. In 1949, Walton made his first record for the small record label, Spire Records in Fresno.

The track was "Lonesome Cabin Blues". Shortly after that, he had a national hit on Specialty Records with "One Room Country Shack", now considered a blues standard.[4] After that success, he was able to start working as a musician full-time, and he toured with the jump blues band of Big Jay McNeely.

A half dozen tracks recorded for the Flair Records label in 1955, included "Come Back Maybellene," a sequel to Chuck Berry's then-current hit, "Maybellene".

In 1961, Arhoolie Records released an album recorded in Stockton, California entitled Mercy Dee. Featured with him was Sidney Maiden on harmonica, K. C. Douglas on electric guitar and Otis Cherry playing the drums.

Walton died of a cerebral hemorrhage in Murphy, California the following year.