When he was 14 years old, Horford moved to Michigan to live with his father and four of his half-siblings. There, he helped raise his younger siblings, often babysitting them and playing sports in the backyard. Even as a teenager, he was mature beyond his years and took on a fatherly role for his younger siblings. He skipped high school parties to stay home with them and even advised them when they were old enough to attend parties themselves.

As a high school student in Michigan, Horford made an impact with his basketball skills. He played for Grand Ledge High School, and was a standout player on the team. During his junior and senior years, he was named the team's most valuable player and helped lead the team to two district championships.

Horford's skills on the basketball court caught the attention of college scouts, and he ultimately chose to attend the University of Florida. During his time at Florida, he won two national championships and was named SEC player of the year in his junior year. He was drafted into the NBA in 2007 by the Atlanta Hawks, where he spent the first nine years of his professional career.