Femi Adebayo was born on July 18, 1997 in Newark, New Jersey to a Nigerian father and an African-American mother. As a child, he was given the nickname “Bam Bam” by his mother when, while watching The Flintstones at age one, he flipped over a coffee table in a manner similar to the show’s character Bamm-Bamm Rubble. Adebayo is of African American and Yoruba decent.Adebayo first attended Northside High School in Pinetown, North Carolina. As a junior, he averaged 32.2 points and 21 rebounds a game. During the summer, Adebayo joined his Amateur Athletic Union (AAU) team, Team Loaded NC, alongside fellow five-star 2016 recruit Dennis Smith Jr. He averaged 15.0 points and 10 rebounds per game on Adidas Uprising Circuit. Later that summer Adebayo competed at the NBPA Top 100 Camp and was named MVP at the 2015 Under Armour Elite 24 game. After his junior season he transferred to High Point Christian Academy in High Point, North Carolina.
In his season debut, Adebayo scored 22 points and 17 rebounds in an 81–39 win over
New Garden Friends School . On December 29, he posted 26 points and 14 rebounds in a 91–63 victory over De’Aaron Fox and Cypress Lakes High School . As a senior, Adebayo averaged 18.9 points per game , 13.0 rebounds per game , 1.4 blocks per game and 1.5 assist per game, and led the Cougars to a NCISAA state championship appearance Adebayo was named 2016 North Carolina Mr. Basketball In January 2016, Adebayo played in the 2016 McDonald’s All-American Game and Jordan Brand Classic .
Adebayo was rated as a five-star recruit and considered one of the best high school prospects of the 2016 class. Adebayo was ranked as the No. 5 overall recruit and No. 2 power forward in the 2016 high school class.
Adebayo was cut from the United States national team for the 2019 FIBA Basketball World Cup. He was subsequently named a finalist for the U.S. Olympic team in February 2020.