Thomson, a three-time All-Star who played for the Giants and four other clubs, had been in declining health and died at his home in Savannah, Ga., according to multiple news reports.
Thomson's ninth-inning home run off the Dodgers' Ralph Branca clinched the 1951 National League pennant for the Giants, or as announcer Russ Hodges put it as Thomson rounded the bases and the Polo Grounds turned to bedlam: "The Giants win the pennant! The Giants win the pennant! The Giants win the pennant!"
"Bobby Thomson will always hold a special place in our game for hitting one of the signature home runs in baseball history," Commissioner Bud Selig said in a statement issued Tuesday. "'The Shot Heard Round the World' will always remain a defining moment for our game, illustrating the timeless quality of the national pastime."
Thomson once recalled, "Right away after I hit it, I thought it was a home run. Going around the bases, I could hardly breathe. I was starting to hyperventilate."
After breaking in with a strong rookie season in 1947, Thomson played parts of 15 seasons in the Majors, also suiting up for the Milwaukee Braves, the Cubs, the Red Sox and the Orioles before retiring in 1960. Primarily an outfielder who also played second and third, Thomson was a .270 career hitter with 264 home runs and 1,026 RBIs in 1,779 games. He was an All-Star in 1948, '49, and '52.
But that one swing and that one shot defined his career and made him a legendary name in the sport.
"Bobby's baseball career was highlighted by that long drive at the Polo Grounds on October 3, 1951, but 'The Flying Scot' was an accomplished, three-time All-Star in a 15-year Major League career," Selig said. "A true gentleman, Bobby was a perfect choice to have earned one of the game's most memorable moments."
Giants managing general partner and chief executive officer William H. Neukom echoed Selig's sentiment.
"While Bobby was so well known throughout the world as the man who hit the most famous home run in baseball history, he was also a true gentleman who showed the respect for the game and carried himself with dignity that is so important to baseball," Neukom said in the club's official statement.
Branca, who delivered the pitch and over subsequent years became friends with Thomson, said Tuesday the quality of the man is why they bonded, not just their shared place in baseball history.
"We had become close friends," Branca said in a telephone interview with MLB.com. "People wonder why, but basically we had the same values. We both loved America, loved our country, and he was a good family man. ...
"I respected him. He never lorded it over me. I think he understood my position. We never talked about the pitch and what happened."
In 1951, the Dodgers had held a seemingly insurmountable 13-game lead on Aug. 11 over the Giants, their crosstown National League rivals. But the Giants went 37-7 the rest of the way, and the two teams ended the season in a tie, forcing a three-game playoff to decide the NL pennant -- and setting up Thomson's historic swing.
That it was Thomson who delivered such a clout on such a big stage was less shocking than the outcome. Thomson was an MVP candidate that 1951 season, hitting 32 homers with 101 RBIs. He already had driven in the Giants' first run that day and had hit a two-run homer off Branca in the opener of the best-of-three series.
But when he came to the plate that Oct. 3 with one out in the ninth, Thomson could have no idea he was about to become a legend. As Giants baserunner Don Mueller was attended to and replaced after injuring his ankle sliding into third, Dodgers manager Chuck Dressen pulled starter Don Newcombe after he had given up three base hits to allow the Giants to pull within two, 4-2, bringing Thomson to the plate against Branca.
"I walked out to talk to [Giants manager] Leo [Durocher] and he said: 'If you ever hit one, hit one now.' I could see he was plenty excited, too, and I calmed down a bit," Thomson once recalled. "On my way back to the plate, I said to myself: 'You're a pro. Act like one!'"
With future Hall of Famer Willie Mays waiting on deck, Thomson turned on an 0-and-1 pitch and sent it into the bleachers at the Polo Grounds. One of the greatest celebrations in baseball history unfolded on the field as Thomson came to home plate, jumped up and landed on it and was mobbed by his teammates.
Branca struggled with back problems and retired in 1956, while Thomson moved on to the Braves, where his 1954 Spring Training injury opened the door for future Hall of Famer Hank Aaron. After a brief return to the Giants in 1957, Thomson closed out his career with the Red Sox and Orioles in 1960. But they always had The Shot.
"People say, 'Did I think it would last this long?' and I say, 'No,'" Branca said. "I thought probably the next year somebody would hit a home run and they'd forget all about it, or the following year. But it was the neighborhood rivalry ... and it was the media capital of the world."
The pitcher and the hitter appeared together at memorabilia shows and other events over the years, though their relationship eventually was strained following a Wall Street Journal report in 2001 alleging that the Giants were stealing signs, so therefore Thomson knew what pitch was coming. Branca took that as some measure of vindication for giving up the famous homer, but Thomson always maintained he had no help.
Stories surrounding the homer have emerged over time. Yogi Berra, then the Yankees' All-Star catcher, missed the homer, because he was driving home after watching part of the game -- so much for "It ain't over till it's over." And in an age when such a baseball might fetch a hefty sum of money, the ball from The Shot never surfaced, and its location remains a mystery. Thomson said he might have had it for some World Series tickets, though.
"The next day, [a fan] had the ball I hit and said, "Bobby, I'll let you have this ball if you get me two tickets to the game today," Thomson said. "But I remember thinking it was impossible."
Peter Magowan, who was the managing general partner of the Giants from 1993-2008, was 9 years old at the time of the homer, listening to the game on the radio in class. Later, he was honored to have become friends with Thomson -- and said he actually had tried to reach Thomson by phone on Monday.
"He was a very kind person, very thoughtful, a gentle man," Magowan said. "He always stood up for a lady. He was really a courtly, well-behaved gentleman. Just nice to everybody. ...
"I'm sure that a lot of people can tell you where they were when JFK was assassinated or on 9/11, but I also think there are a lot of people who will tell you what they were doing on Oct. 3, 1951."
Thomson was born in Glasgow, Scotland, and came to the United States in 1926 when he was 3. He grew up in Staten Island, N.Y., and after signing a contract with the Giants in 1942, he spent three years in the U.S. Army Air Force during World War II. He is survived by two daughters, Megan and Nancy.
"He was a real gentleman and I think he handled his role well, too, being the hero of that series," former Brooklyn pitcher Carl Erskine, who was warming up in the bullpen when Branca was summoned, told The Associated Press. "I think he and Branca turned that incident into two real pros who handled that in a real class way."
John Schlegel is a reporter for MLB.com. National correspondent Ben Platt contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.