TMZ Sports talked to P and Hercy -- an 18-year-old, 6'3" senior point guard at Minnehaha Academy in MN -- moments after the younger Miller announced he was choosing Tennessee State over the likes of USC, UCLA, Missouri, LSU and other Power 5 conference programs.

We asked Miller why he passed on schools that produced NBA stars like Russell Westbrook, Kevin Love, Ben Simmons, and DeMar DeRozan ... and his answer was powerful.

"I want to go a place with a good school, and I feel like if I go to a HBCU, I can put a spotlight on for all the HBCU’s around."

Hercy continued ... "I want to make a change. I want to make a difference. I’m the type of person, I want to be a leader, I want to lead my people. So I feel like going to Tennessee St. University is where I can be a part of the community and be a player at the same time."

Hercy -- whose brother Romeo played 2 seasons at USC -- says he has plans to play in the NBA ... something Master P says will NOT be an issue coming from an HBCU.

"If you look at the conference, Ja Morant played in the same conference. This is not just a regular school. This is a big conference that put a lot of pros into the league."

Of course, Morant went to Murray St. and was the 2nd overall pick in the 2019 NBA Draft ... right after Zion Williamson.

Robert Covington -- Portland Trailblazers small forward -- attended Tennessee St. ... and has had a very solid NBA career.

As for P -- a legendary musician who played in the NBA, made movies and earned millions in the business world -- where does watching his young son commit to play college ball rank on his list of accomplishments?

"This is at the top of the totem pole for me."