Co-offensive coordinator and offensive line coach Shawn Elliott has been named the interim coach and will replace Spurrier for the remainder of the season, sources confirmed to ESPN on Tuesday morning. The coach's weekly news conference is still scheduled to be held at noon Tuesday.
Spurrier, the Gamecocks' all-time winningest coach, also informed South Carolina athletic director Ray Tanner of his decision to step down, sources said. The announcement came after the Gamecocks lost their fourth straight SEC game Saturday to LSU. The loss guaranteed Spurrier could do no better than a .500 season.
Spurrier's retirement was first reported by SI.com.
Players and even rival coaches took to Twitter to react to the news.
"I hate it for Steve and hate it for college football," Alabama coach Nick Saban told ESPN. "The guy's been one of the best coaches for a long, long time and a great personality for the game. I have a tremendous amount of respect for what he's accomplished and what he's done. ... It's always sad to see somebody who's meant so much to the game walk away."
Said Oklahoma coach Bob Stoops, a former assistant under Spurrier at Florida: "He's probably the most competitive guy I've ever known, but he's also one of the most genuine guys I've ever known. He's special."
Spurrier, 70, was close to stepping down at the end of last season, when the Gamecocks dipped to 7-6 after three straight 11-win seasons and three straight top-10 finishes, but he elected to return. The Gamecocks have lost eight of their past nine SEC games dating to last season.
The Gamecocks are 2-4 overall this season and 0-4 in the SEC. They sit seventh in the SEC East.
Spurrier, fed up with age questions and critics suggesting his best coaching days were behind him, went on the offensive before this season began.
"We were 11-2 and ranked fourth in the country this time a year ago, and nobody said a damn word about my age," Spurrier said. "Now, a year later, I'm suddenly too old, and we're on our way down.
"I just want our fans to know that we're going to have a good team and recognize that it's our enemies saying these things about Spurrier being washed up and we're not going to be heard from again. Gamecocks out there need to know that I'm going to be here five or six more years, and away we go."
Spurrier said then that he wasn't going to let one down season derail the momentum the program had built since going to the SEC championship game in 2010. Before he arrived in 2005, South Carolina had one season of double-digit wins in its history.
"I'm smart enough to know when it's time to let somebody else come in and do this, but I'm also smart enough to know that we've beaten Georgia four of the last five years, beaten Florida four of the last five years and beaten Clemson five of the last six years," Spurrier said in July. "We're only 3-2 against Tennessee the last five years, and they won a couple of close ones against us, but they've lost 10 in a row to Florida. So I'd say we've done OK and have a lot more we're going to do."
Spurrier has an 86-49 record at South Carolina and a 228-89-2 mark in 25 seasons as a head coach. He coached Florida, his alma mater, from 1990 to 2001 and led the Gators to the 1996 national championship and six SEC championships. He has been named SEC coach of the year nine times.
In addition, Spurrier had brief stints at Duke and with the NFL's Washington Redskins.
He won the 1966 Heisman Trophy as Florida's quarterback and played for San Francisco and Tampa Bay in the NFL.
Spurrier became South Carolina's winningest coach, getting 65 victories to surpass Rex Enright, in the 2012 season finale. He is also Florida's winningest coach (122 victories), and he and Paul "Bear" Bryant are the only coaches to record the most wins at two SEC schools. Only Bryant, with 159, has more SEC wins than Spurrier's 135.
The Gamecocks play at home against Vanderbilt (2-3, 0-2) on Saturday.
ESPN.com's Mark Schlabach and The Associated Press contributed to this report.
Why is Spurrier retiring?
ESPN's Joe Schad provides insight as to why Steve Spurrier is stepping down as the South Carolina head coach in the middle of the season.
Steve Spurrier is retiring
South Carolina coach Steve Spurrier is retiring immediately. An interim coach will be named Wednesday.