FSU coach Bobby Bowden made the surprising announcement at his weekly luncheon on Monday.
While the news was met by silence from the audience, the Seminoles say they back the decision of Bowden and the coaching staff.
Rix hasn't started since the season's third game at home against Clemson. He was knocked from the contest by a high ankle sprain and eventually lost the starter's role while he recovered to effective Sexton.
Sexton started five consecutive games before faltering at Maryland. He was replaced in the fourth quarter by Rix at Maryland on Saturday.
"If Coach Bowden supports it, then we support it," receiver Willie Reid said at the luncheon.
"We go along with whatever Coach Bowden decides. Coach Bowden is the head of the team."
Still, Reid admitted the move caught him off guard.
Sexton was 14 for 30 for 164 yards in a 20-17 loss to Maryland last Saturday and was relieved by Rix, who went 8-for-21 for 140 yards and a touchdown pass.
"I think it's caught everybody by surprise," Reid said.
"I wasn't expecting any changes, but coaches makes changes for the best. You just have to get back used to Rix playing because different quarterbacks, you look for different things. It's a different feel out there for them.
"It's just comes back to now we have to really come together as a team trying to finish out the season with three wins. We're not playing what we want to play for (national title), but we still have a lot to salvage. We still have a lot of fans to impress and make happy."
Bowden elaborated more on the move following the luncheon, focusing on Sexton's stability versus Rix's mobility.
"Maybe we need more than stability," Bowden said.
"Let's take a chance and see if we can get something more on that board. And if we're wrong, we can always change back. It ain't like this is your last move.
"Chris comes in at a critical time (against Maryland) and we get a touchdown, and he sets up a couple of field goals. Knowing I got to go to N.C. State (next Thursday), we're going to go ahead and take a shot at it.
"The other night, I know it was awkward and ugly at times, but he did enough for us to win the darn game."
At his weekly meeting with the media on Monday afternoon, FSU offensive coordinator Jeff Bowden said he also was in agreement with the switch.
"I was in agreement Saturday with the change when we made it, because I felt like we needed mobility with doing so much shotgun," Bowden said.
"I think we feel like Wyatt does some things better than Chris and, on the other hand, Chris will do some things better than Wyatt."
Bowden believes the Seminoles rallied behind Rix, who threw a fourth-quarter touchdown against the Terrapins.
"The attitude was great when Chris came in," Bowden said.
"There wasn't any panic out of the kids. The one thing that can really hurt man coverage is a guy that can buy time like Chris can, because you can't cover for that long.
"He (Rix) looked like he threw with adrenalin, 100-percent full. Let him know he's the starter with a week of practice and hopefully you'll see a little different version."