The announcement was made about an hour after the Eagles defeated The Citadel, 13-6, at Paulson Stadium in the regular-season finale.
"We just felt the time was right to do this," Georgia Southern athletic director Sam Baker said in a hastily arranged news conference at the stadium.
"We didn't think next year was going to be any different than this year. (So let's) go ahead and make the change and start anew and go ahead and get to working toward making our program one of the best in FCS football."
The Eagles finished 5-6 -- only the school's third losing campaign since restarting football in 1982. Hatcher, who did not return phones calls Saturday night, was 18-15 in three seasons.
The announcement was probably a shock to coaches and players, who expressed optimism about the upcoming season during a postgame news conference.
Georgia Southern had 30 freshmen and sophomores on the two-deep depth chart.
But there had been plenty of talk about a change. Some centered around Baker.
"Coach (Hatcher) tells us not to listen (to negative talk)," said freshman wide receiver Mitch Williford. "People don't know what happens behind the scenes. We all love coach Hatcher. You can't put all the blame (for a losing season) on Sam Baker and coach Hatcher. There are players who have to perform."
Hatcher might not have had a chance to tell his players of the change. He did his taped coach's show after the game before being told of the decision by Baker and Ron Core, the school's vice president of business administration. Baker reports to Core.
Hatcher came to the Eagles known as an offensive guru, and his scheme was known as "the Hatch Attack."
Hatcher changed his philosophy in 2007 to incorporate the running talent of senior quarterback Jayson Foster. The Eagles missed winning the Southern Conference title when a short field goal went wide against Furman.
Without Foster the next season, Hatcher decided to implement the passing attack. The Eagles finished 6-5 and seemed to take a step backward this season.
"I'm sure (the fans) are upset we're not winning," said Hatcher after Monday's practice. "We're doing the best we can right now. We haven't stopped working. If the fans are disappointed, I can assure you no one's more disappointed than I am.
"It takes time to rebuild something and unfortunately, we're in that process right now."
Georgia Southern officials didn't want to wait. School president Bruce Grube, whose tenure ends Dec. 31, was in attendance at the news conference. He said incoming president Brooks Keel supported the change.
Baker didn't rule out a return to the triple option offense that was run so successfully at Georgia Southern before he fired Mike Sewak. He said he didn't have a successor in mind.
Former Eagles All-American Giff Smith, now an assistant coach at Georgia Tech, could be among the leading candidates to replace Hatcher. Ivin Jasper, an assistant coach at Navy, and Georgia Tech assistant Jeff Monken also have been mentioned. Both worked under former Georgia Southern coach Paul Johnson, who is in his second season leading Georgia Tech's program.
Reach Donald Heath at firstname.lastname@example.org.
Chris Hatcher took over at Georgia Southern in 2007, only weeks after Brian VanGorder resigned. Hatcher had a distinguished coaching career at Valdosta State (76-12), winning the Division II national championship in 2004.
THIS SEASON: Hatcher and the Eagles finished 5-6.
OVERALL: Hatcher was 18-15 in three seasons.