Tournament MVP Isiah Wilkins led the Lancers with 19 points and eight rebounds while Leslie Nkereuwem added 11 points and six boards.
D.J. Burns Jr. paced the Eagles with 14 points and six rebounds. Micheal Anumba added 12 while Patrick Good came off of the bench to add 11.
Story of the game
After trailing by as many as 16 in their semifinal game, Longwood was determined to get off to a fast start in the most important game in school history and they did.
A putback by Jordan Perkins put the Lancers ahead 9-2 and after a further 5-0 run made it a 17-6 game, Winthrop was forced to call a timeout.
The Longwood defense then stepped up to force turnovers and Perkins finished at the other end to cap off another run, this one 10-0, to push the lead to 27-10.
Burns Jr. hit a jumper that cut it to 13, but a 7-0 spurt made it 34-14 and the top seed led 45-27 at halftime thanks to a blistering 60 percent from the floor, including eight of ten from behind the arc.
A pair of basket by Burns Jr., the Big South Player of the Year, cut it to 15, but after a timeout the Lancers essentially put the game away with a 13-0 run to open up a 62-34 advantage.
Winthrop tried their best to stay competitive, scoring 12 of the next 16 points and back-to-back threes by Good and Russell Jones. Jr cut it to 18 with 8:30 left.
Longwood maintained their big edge despite an Anumba three with 2:16 left that made it a 16-point game. The Lancers celebrated as they picked up their 26th win of the season.
"Today was just a special performance by the Lancers", said head coach Griff Aldrich. "This year's just been incredibly special at Longwood.
"I really believe Longwood is a special place. We've got so many wonderful ingredients. The building blocks are there, for a great university, a great community and I do want to say incredible support from our president.
"There's been incredible support to build a sustainable program, not just a successful team and that is our goal."
Wilkins added: "thank god I found somebody like Coach Griff to sweep me out of the transfer portal and allow me to play with this great group of guys and win this championship."