Martin Baron, a newsroom giant who led The Washington Post, The Boston Globe and The Miami Herald to numerous Pulitzer Prizes in a storied journalism career, said today that he would retire Feb. 28 after eight years as The Post’s executive editor.

“At age 66, I feel ready to move on,” he said in a note to the newspaper’s staff.

Baron said that he had joined the paper with “a reverence for The Post’s heritage of courage and independence and feeling an inviolable obligation to uphold its values,” and that the news staff had delivered “the finest journalism.”

“You stood firm against cynical, never-ending assaults on objective fact,” he wrote.

His years as executive editor started in January 2013, weeks before former President Barack Obama was sworn in for a second term, and spanned all of President Donald Trump’s time in the White House. Trump frequently denigrated The Post, calling it “fake news,” “the enemy of the people” and “crazed and dishonest,” among other insults. In 2017, The Post adopted the first official slogan in its more than 140-year history: “Democracy Dies in Darkness.”

Baron’s decision to leave did not come as a surprise. He had previously committed to staying at the paper only through the 2020 election.

He joined The Post after a red-hot run of more than 11 years as the top editor of The Boston Globe, which won six Pulitzer Prizes during his tenure. He oversaw The Globe’s Spotlight team of investigative journalists, who reported an ambitious series on a pattern of sexual abuse by clergy in the Roman Catholic Church and the decadeslong effort to cover it up. The stories earned the paper the 2003 Pulitzer in the public service category. (The Globe was owned by The New York Times Co. from 1993 to 2013.)

The investigation, comprising more than 20 articles, became the basis of the 2015 Oscar-winning film “Spotlight,” in which Baron was played by Liev Schreiber. In a 2016 article, Baron conceded that Schreiber had captured his newsroom demeanor, writing, “His depiction has me as a stoic, humorless, somewhat dour character that many professional colleagues instantly recognize (‘He nailed you’) and that my closest friends find not entirely familiar.”

Before joining The Globe in 2001, Baron, who grew up in Tampa, Florida, was the top editor of The Miami Herald, which won a Pulitzer in breaking news under his leadership. He also held top editing jobs at The New York Times and the Los Angeles Times. He started his career in 1976 as a reporter at The Herald.

Baron said The Post was now “well positioned for the future,” with a greater readership, broadened coverage and more journalists that it had on his arrival.

“We have now created a truly national and international news organization,” he said.

The Post now has about 3 million digital-only subscribers, up by nearly 1 million in the last year. Its newsroom has grown, from 580 journalists when Baron arrived to more than 1,000.

Baron took charge of the newsroom when The Post was owned by the Graham family, the caretakers of the paper for three generations. At the time of his arrival, The Post was struggling financially as it dealt with the battles all legacy newspapers have faced: declining print ad revenue, plummeting circulation and new competition from digital news outlets.

In August 2013, Jeff Bezos, founder of Amazon, bought it for $250 million. Since then, the combination of Bezos’ resources and Baron’s newsroom know-how has revived a newspaper famous for its reporting, by Bob Woodward and Carl Bernstein, on the Watergate scandal that toppled President Richard Nixon.

Woodward, an associate editor who started at The Post 50 years ago under executive editor Ben Bradlee, said Tuesday he had hoped Baron’s retirement would have come a bit later.

“It’s just an amazing job he’s done,” Woodward said. “The high bar for an executive editor of The Washington Post is to fill Ben Bradlee’s shoes. Marty did it fully, with intense engagement.”

Margaret Sullivan, The Post’s media columnist and a former public editor of The Times, said it had been a privilege to work for Baron. “I think he is a truly outstanding editor and that American citizens owe him a standing ovation for the work he’s done as editor of The Washington Post and for the work he’s done in the past,” she said.

Bezos weighed in on Baron’s planned retirement in an Instagram post Tuesday that addressed his departing editor directly: “Our success these past several years would not and simply could not have happened without you,” he wrote.

He described Baron as “both swashbuckling and careful,” saying he had led the paper with integrity, “even when it was exhausting.”

During Baron’s time as executive editor, The Post won 10 Pulitzer Prizes, including the 2020 award in the explanatory reporting category for a series on the effects of climate change.

“Please don’t lose sight of how hard our gains as a commercial enterprise were to achieve. They would be easy to lose,” Baron wrote. “In 2013, when our outlook was dire, we were given a second chance. We took it, engineering a turnaround with focus and creativity.”

He acknowledged that more work remained to be done at The Post, including increasing diversity in the newsroom and a deepening its understanding of the communities it covers.

“From the moment I arrived at The Post, I have sought to make an enduring contribution while giving back to a profession that has meant so much to me and that serves to safeguard democracy,” Baron wrote.

In a note to employees Tuesday, The Post’s publisher and chief executive, Fred Ryan, said that, although he had known Baron’s retirement would come, it “does not lessen the emotion we feel.”

“Under Marty’s eight years of newsroom leadership, The Washington Post has experienced a dramatic resurgence and has soared to new journalistic heights,” Ryan said.

The Post will have a “broad and inclusive” search for a successor that will include internal and external candidates, Ryan added.

“Please know that I view this as one of the most consequential responsibilities I will have as your publisher,” he said.