Baker Reagan Mayfield was born on April 14, 1995, in Austin Texas, to James and Gina Mayfield as the second of two sons. Mayfield grew up as a fan of Oklahoma, and he attended a number of their games during his childhood.
Mayfield was the starting quarterback for the Lake Travis High School Cavaliers football team. He led Lake Travis to a 25–2 record in two seasons and won the 2011 4A State Championship. He finished his high school football career totaling 6,255 passing yards, 67 touchdowns, and eight interceptions.