Allen attended Sheldon High School in Sacramento, California, where he was a standout four-year varsity basketball player.

[6] After graduating from college, Allen went undrafted in the 2017 NBA draft, making him an unrestricted free agent.

[11] Later in 2017, he made it onto the Salt Lake City Stars team via a local tryout prior to the start of the 2017-18 NBA G League season.

[11] Eleven days later on January 28, 2018, the Agua Caliente Clippers picked up Allen via the G League available player pool.

[21] In July 2024 Allen sued the Elk Grove, California Police Department, accusing them of breaking his knee with baton strikes after he was found sleeping in a car.