The new name was revealed in a video on the team's Twitter page. The presentation was narrated by the Oscar-winning actor Tom Hanks, and included accompaniment from the Black Keys and lasted a little more than 2 minutes.
The montage included landmarks and scenery of Cleveland and a handful of baseball highlights.
Those baseball scenes included footage of the late Frank Robinson, a Hall of Fame player who also became MLB's first Black manager, when he took over the Cleveland dugout in 1975.
“We remember those moments as we move forward with change," Hanks narrated.
"Together we stand with all who understand what it means to be born and built from The Land. Because this is the city we love and the game we believe in and together we are all Cleveland Guardians.”
The video also unveiled a new team logo of a baseball, with winged Gs.
"Guardians" also pays tribute to the nearby Hope Memorial Bridge, which goes over the Cuyahoga River and includes statues called the "Guardians of Traffic."
The team's colors of red, white and navy blue remain the same.
Friday's announcement capped a monthslong process that involved contact with 40,000 fans, as well as interviews with fans, community leaders and front office personnel, which generated an initial list of 1,198 potential team names, club officials said.
"We're trying to be the best Cleveland organization we can be and be united for everybody and representing the city of Cleveland like it deserves," Manager Terry Francona, who has long ties to the city and the team, told reporters.
His father, Tito Francona, played big league baseball for 15 season and six of his most productive campaigns were as a Cleveland outfielder from 1959 through 1964.
The younger Francona also played in Cleveland and has been the manager since 2013, leading his team to the 2016 American League pennant.
"I think it look a lot of guts and a lot of bravery," Francona said of the decision to change the team name.
"We are trying to be the most respectful we can. And It's not about us. It's about other people. And you have to step outside of your own skin and think about people who may have different color skin and what they're thinking."
As fans speculated these past few months about Cleveland's new name, the Guardians had been considered among the favorites, along with the Spiders, Naps and Rockers.
The Cleveland Spiders were a 19th century baseball team. The American League franchise was known as the Naps in the early 20th century in a nod to star player Nap Lajoie. And the Rock & Roll Hall of Fame is located in Cleveland.
For years, it was believed the team was named in honor of Spiders great Louis Francis Sockalexis, who was Native American.
But a closer examination of historical record showed the team was more likely grasping for a Native American-themed name following the great run of the 1914 Boston Braves. Those "Miracle Braves" captured the nation's imagination with an improbable world title, rallying from last place July 4.
The Cleveland team, known as the Indians since 1915, has won six American League pennants and two World Series titles. That last world championship was captured in 1948, making it the MLB's longest current title drought.
The Cleveland baseball name change comes in the wake of Washington, D.C.'s professional football team dropping its Native American moniker.
It's now known as the Washington Football Team. The name changes came as Americans took the streets in protest against police brutality and systemic racism following the killing of George Floyd in Minneapolis.