The story was first reported by The Boston Globe.
Varitek's wife, Catherine, congratulated her husband for his fine career on Twitter, posting from @catherinevaritek, "I could not be more proud of my husband! What a truly remarkable 14 years with the Boston Red Sox. You are a true Champion! #RedSox #Captain"
He retires as the all-time leader in games caught for the Red Sox at 1,488.
There's a strong chance Varitek will remain with the Red Sox in some capacity, something general manager Ben Cherington hinted at during the offseason.
Varitek, 39, served as Boston's captain for his last seven seasons with the Red Sox, but he was their de facto leader long before that.
The switch-hitter's retirement comes roughly two weeks after his long-time teammate Tim Wakefield called it a career.
"He's one true champion and I'm proud to be able to say I was his teammate for 15 years," Wakefield said of Varitek on Feb. 17.
The catcher Varitek competed against most often in his career, the Yankees' Jorge Posada, announced his retirement a month ago.
Varitek came to the Red Sox on July 31, 1997, along with Derek Lowe in a trade with the Mariners for reliever Heathcliff Slocum in what wound up one of the most one-sided trades in team history.
After working his way up the chain in the Mariners' farm system, Varitek made his first Major League start for the Red Sox on April 2, 1998, and he would remain as a fixture for 14 seasons.
Varitek played in 1,546 games, hitting .256 with 193 homers and 757 RBIs. But the numbers never demonstrated Varitek's true worth, something that could best be seen in meetings with his pitchers or by the hours he spent at his locker pouring through scouting reports.
"I don't think you're going to find anybody in there that's not going to say they'll miss him, and likewise for Wakey," Red Sox righty Josh Beckett said recently. "If 'Tek doesn't come back, he's going to be missed severely, both in the clubhouse and out in the field."
Blocking the plate was another Varitek specialty. There were numerous occasions over the years when it seemed the Red Sox were going to give up a run on a base hit, but Varitek risked personal injury by hauling in the throw from the outfielder and preventing that baserunner from touching his turf -- home plate.
When the Red Sox acquired Victor Martinez on July 31, 2009, Varitek transitioned to a backup role.
Some wondered if Varitek could still be an effective captain while serving as a part-time player. He answered that question swiftly and actually embraced the new role.
But it was during his decade as Boston's primary catcher that he made his biggest mark.
On July 24, 2004, the Red Sox had been in a fog as a team and trailing against the Yankees. Alex Rodriguez barked at Bronson Arroyo after being hit by a breaking pitch. Varitek suggested to A-Rod that he get to first base. Rodriguez got in Varitek's face and an altercation ensued.
The Red Sox won that game in dramatic fashion on Bill Mueller's walk-off homer off Mariano Rivera, and many players cited that day as a key unifying development in what turned out to be an epic season.
Varitek was a three-time All-Star and won the Gold Glove in 2005.
Varitek spent much of last season mentoring Jarrod Saltalamacchia, who is now Boston's primary catcher.
"There's a lot of little things as far as catching that I learned [from Varitek]," said Saltalamacchia earlier in Spring Training. "It's mainly to be good person, be a good teammate and respect the game. One thing, he signed a jersey for me, and on it, it said, 'Catch with pride.' You take that and that's just kind of what he's done his whole career. I'm going to do the same."
Much like Wakefield, Varitek was hoping to make one more run with Boston. But after signing Kelly Shoppach as a backup in December, all the Red Sox had open for Varitek was a non-roster invitation to Spring Training.
It would have been hard to imagine a long-time captain coming to camp competing for a job, and that scenario never unfolded, as Varitek instead decided to end a solid and memorable career on his terms.