Mayfield Pennington was born in Pikeville, Kentucky.
Pennington had an amateur record of 38-3.
On his gym's website, Pennington's professional record is listed as 48-16. The 1979 Ring Record Book states "complete record unavailable."
Pennington died from injuries suffered in a traffic crash in Eastern Kentucky on February 12, 2013. According to police, Pennington was trying to pull onto the southbound lanes of U.S. 23 in Floyd County when he lost control of his car and started facing northbound in the southbound lanes. His Corvette ended up off the road and under the front right tire of a tractor trailer.