Josiah Parker grew up in the Dayton suburb of Huber Heights and prepped at Combine (NC) Academy, where he earned a #90 national ranking at 247Sports.com and committed to Florida Atlantic in September 2024 over offers at Missouri, TX-Arlington, and Miami (OH). A four star recruit, he was the highest-ranked recruit to date for the FAU program and joined his brother Demond, who was an assistant coach there.

Parker started the final eight games of the season for FAU en route to averages of 9.6 points and 6.0 rebounds in 32 games overall, and was named the American Conference's Freshman of the Year in its post-season awards.