The honors were determined by an online fan poll in April and May, with 25.5 million votes cast.
The quartet appeared on the field at Great American Ball Park before the Midsummer Classic.
"What an experience to see those guys come out on the field," Houston Astros left-hander Dallas Keuchel, the American League's starting pitcher, said on the FOX telecast. "What a humbling experience to be out on the same field with them."
Major League Baseball also announced the four selected as the greatest Negro Leagues Players -- Cool Papa Bell, Josh Gibson, Buck O'Neil and Satchel Paige -- and the greatest pioneers (career began 1915 or earlier) -- Walter Johnson, Nap Lajoie, Christy Mathewson and Cy Young.
In addition, "Franchise Fours" were picked for each of the 30 major league teams.
Nolan Ryan was chosen as one of the four greatest players on three franchises -- the Los Angeles Angels, the Houston Astros and the Texas Rangers. Vladimir Guerrero was one of the honorees for the Angels and for the Washington Nationals. He starred for the Montreal Expos, who later became the Nationals.
Fifteen active players made the cut.
Texas Rangers third baseman Adrian Beltre, Detroit Tigers first baseman Miguel Cabrera, Arizona Diamondbacks first baseman Paul Goldschmidt, Seattle Mariners right-hander Felix Hernandez, Tampa Bay Rays third baseman Evan Longoria, Boston Red Sox designated hitter David Ortiz, San Francisco Giants catcher Buster Posey, Miami Marlins right fielder Giancarlo Stanton, Angels center fielder Mike Trout, Colorado Rockies shortstop Troy Tulowitzki and New York Mets third baseman David Wright all were honored for their current teams.
Tigers left-hander David Price, San Diego Padres right-hander James Shields and Oakland A's utility man Ben Zobrist made the Rays' all-time team. Marlins outfielder Ichiro Suzuki was honored as part of the Mariners' team.
The team-by-team "Franchise Fours," as selected by an online vote (players listed alphabetically):
Los Angeles Angels -- Vladimir Guerrero, Nolan Ryan, Tim Salmon, Mike Trout
Tampa Bay Rays -- Evan Longoria, David Price, James Shields, Ben Zobrist
New York Mets -- Keith Hernandez, Mike Piazza, Tom Seaver, David Wright
Washington Nationals -- Gary Carter, Andre Dawson, Vladimir Guerrero, Tim Raines