The Tigers routed third-seeded Delta State 80-59 to reach this point.
No historically black college team has won a Division II title since Virginia Union in 2005.
"A lot of people are like, 'Who are these guys from Tuskegee coming here from the HBCU conference that they're in?'" Tuskegee forward Richard Dixon said. "I know we're shocking a lot of people right now. They're trying to figure out who these guys are on this team."
The Tigers had different leading scorers in all three regional games.
Dixon, who's leading the team in scoring at 17.3 points per game despite starting only one game, scored 22 against North Alabama in the second round.
Kevin May had 24 points — 17 more than his season average — against Delta State, while Elliot Dean scored 31 against Florida Southern.
Douglas has led Tuskegee to four regular-season Southern Intercollegiate titles and two SIAC tournament championships over the past eight seasons, breaking droughts of several decades in both regards. They'd never finished better than third in a regional.
He was the first Alabama player picked in the opening round of the NBA draft in 1976, when the Detroit Pistons picked him fourth. Douglas spent eight seasons in the NBA.
Taller than any of his current players, Douglas now has Tuskegee three wins away from a title after the surprising run.
His pre-game message appropriately was about faith before the Delta State game. He put four Bible verses and nothing basketball-related on the board in the locker room: Philippians 4:13, Romans 8:28, Isaiah 54:18 and Matthew 17:20.
Douglas sums up the final verse: "If you believe, you can move mountains."
"There was only a handful of people who believed we could get this far and we turned everybody else out," guard Camden Foster said. "We just kept the 15 in the locker room on the team. We bonded at the right time of the season and we got the job done.
"Here we are making history, and we hope to win it all."