In November, on the 70th anniversary of Mao Anying’s death, the academy served up another version. Citing what it said were declassified telegrams and eyewitness accounts, the academy said in a social-media post that Mao was killed after enemy forces detected radio transmissions from his commander’s headquarters.

“These rumormongers have tied up Mao Anying with egg fried rice, gravely dwarfing the heroic image of Mao Anying’s brave sacrifice,” said the post, which has attracted about 1.9 million views. “Their hearts are vicious.” The academy attributed the egg fried rice story to the 2003 edition of a Chinese military officer’s memoir. It didn’t mention the book was published by the Chinese military’s official press.

The history academy is run by Gao Xiang, a 57-year-old historian turned propaganda official who has mixed traditional scholarship with viral marketing techniques to repackage the past in support of Mr. Xi’s vision for a resurgent China.

Mr. Gao and his academy are part of Mr. Xi’s push to harness history in the run-up to the Communist Party’s 100th anniversary this summer. Those efforts have culminated in a national propaganda campaign to promote party history, launched in February, that experts describe as China’s largest mass-education drive since the Mao era.

China’s Communist Party, like its counterpart once did in the Soviet Union, has a history of manipulating the historical record. Photos were altered to emphasize Mao’s presence or excise purged officials, and history texts and museums were reworked to promote new priorities.

Reformist leader Deng Xiaoping also sought to reinterpret history, in his case criticizing Mao’s mistakes in launching the destructive 1966-76 Cultural Revolution. Deng ushered China out from the shadows of Mao’s dictatorial rule and into an era of collective leadership under which the party’s dominance slipped.

Mr. Xi is seeking to change that by concentrating power in his own hands and reinforcing party control over society, including by updating historical narratives to whip up support for Communist rule.

Some Chinese historians have criticized the new history academy’s methods, decrying them as undignified and unserious. Mr. Gao, though, has rejected conventional historians’ restrained detachment.

“History researchers shouldn’t be cold-eyed observers of times and trends,” he wrote in a newspaper commentary in late 2019. “Historical research must stand atop the commanding heights of our times” to “guide governance and nurture people.”

Neither Mr. Gao nor the academy responded to requests for comment.

Mr. Xi has ramped up efforts to forge what he calls a “correct outlook on history” ahead of the party’s centenary—a milestone moment in his “China Dream” of national renaissance and a chance to cement his legacy as a great leader, alongside Mao and Deng.

With China now facing such external challenges as pressure from the U.S. and questions about its handling of the Covid-19 pandemic, the campaign aims to tamp down introspection about the party’s past mistakes and portray it as an unstoppable force that has endured war and chaos to steer China’s rise.

In April, China’s cyberspace regulator launched an online platform and a telephone hotline for the public to denounce instances of “historical nihilism,” such as statements that criticize party leaders and policies or deny “advanced socialist culture.” Such violations can be punished under legislation that includes a 2018 law protecting the reputations of heroes and martyrs.

In early May, a regulatory official said authorities have dealt with a large number of accounts deemed to be propagating historical nihilism, and directed online platforms to clean up more than two million illegal posts.

Officials commissioned concerts with orchestral renditions of patriotic songs such as “Without the Communist Party, There Would Be No New China.” Bureaucrats and students competed in quizzes testing their knowledge of party trivia. Authorities revised books to play down Mao’s despotic missteps. The education ministry added questions on party history to this year’s college-entrance exams, to “guide students to inherit red genes.”

“Looking back at history, it was in the face of various turbulences and chaos that the Chinese Communist Party was born, grew up and became strong,” wrote He Yiting, former executive vice president of Beijing’s Central Party School, in a newspaper commentary in April.

Chinese and foreign historians say the messaging revives Marxist notions of history proceeding inexorably along a revolutionary trajectory. Burnishing Mao’s legacy, they say, also helps Mr. Xi justify his autocratic style and legitimize his expected bid next year for a third five-year term as party chief.

“The goal is to ensure the party’s survival and strengthen personalized rule at the time of dramatic changes in the global landscape,” said Gao Wenqian, a former Communist Party researcher who helped draft official biographies of Mao and Zhou Enlai before moving to the U.S. after Beijing’s deadly crackdown on the 1989 Tiananmen Square pro-democracy protests.

Pro-Xi propaganda has proliferated recently, as private businesses, law firms and even a Shanghai temple dedicated to the Chinese god of wealth have arranged party-history classes for employees. Party museums and revolutionary memorials reported a boom in “red tourism.” Airlines have staged in-flight singalongs and poetry recitals to teach passengers about the party’s past.

The fanfare is set to peak with a ceremony in Beijing this July, when Mr. Xi is expected to mark the party centenary with a speech that portrays his achievements as the bedrock of a new historical era for China, according to people familiar with the matter.

Mr. Xi, a son of a revolutionary hero, has stressed the importance of controlling narratives about the past. In January 2013, just weeks after taking power, he urged senior officials to guard against hostile forces trying to topple the party by smearing its history.

At Mr. Xi’s behest, the history academy was set up in January 2019 under the aegis of both the party’s propaganda department and the state-run Chinese Academy of Social Sciences, or CASS, giving party theorists direct control over its output.

Its inaugural director, Mr. Gao, is concurrently vice president at CASS, where he has been a leading historian who wrote influential works on the Qing, China’s last imperial dynasty. He ventured into politics in 2016, becoming propaganda chief in the southern province of Fujian and then a deputy head of the national cyberspace regulator, where he helped oversee China’s news and social-media industries.

“In the information age, all sorts of viewpoints flow together like mud and sand, and some erroneous strands of thought have slipped in through the gaps,” including efforts to “distort history and vilify heroes,” he said in a 2018 speech.

Mr. Gao was recently promoted to deputy party secretary at CASS, where he previously served as a regular member of its party leadership body.

Mr. Gao has tried to generate popular appeal for the history academy by tapping outside talent, including a young media producer who attracted attention for writing a rap song that aimed to sell Karl Marx to Chinese millennials.

By churning out folksy social-media content, the academy has established a following online—including about 1.2 million followers on the Twitter -like Weibo platform and more than a half-million on the popular video-streaming service Bilibili. Its posts cover a range of historical topics, including archaeological finds dating back to ancient China and party-approved views on famous historical events and figures.

The academy also has pursued academic work, such as compiling a 30-volume history of China. Last year, it launched a journal, “Historical Review,” that offers commentary on current affairs and invokes history to counter criticism of Beijing’s policies.

In July, the journal featured two articles by Chinese researchers that promoted party narratives about China’s history in denouncing Georgetown University history professor James Millward, a critic of Beijing’s forced-assimilation campaign against Uyghur Muslims in Xinjiang. One article accused Mr. Millward of having “sinister motives” and smearing “vocational-education training centers” in Xinjiang as “political-training centers.”

Mr. Millward said the criticism distorted his writings and echoed how Beijing often mischaracterized foreign censure of its human-rights record as challenges to Chinese sovereignty.

Outside the academy, too, party historians are rewriting the past in ways that support Mr. Xi’s views. Past editions of “A Short History of the Chinese Communist Party,” an authoritative text for general audiences, devoted hefty passages to Mao’s “Great Leap Forward,” a disastrous economic program that led to one of history’s deadliest famines.

The revised version, published in February, excises the earlier edition’s conclusion about the program and its fallout: “This bitter historical lesson shouldn’t be forgotten.” The new version also dropped detailed discussions of Mao’s mistakes in launching the Cultural Revolution, a series of purges against “counterrevolutionary elements” that ravaged Chinese society and left as many as millions of people dead. Instead, it focuses mainly on China’s industrial, technological and diplomatic achievements during that decade.

Also gone are well-known quotations from Deng Xiaoping, including his advice that China should “hide our light and bide our time,” or keep a low profile while accumulating strength. Another was a remark he made in 1989 as he prepared to relinquish his last official leadership post: “Building a nation’s fate on the reputation of one or two people is very unhealthy and very dangerous.”

Meanwhile, chapters were added that describe Mr. Xi as a visionary statesman whose authority as the party’s “core” leader must be upheld.

“Amid ten thousand majestic mountains, there must be a main peak,” reads the updated book, which devotes more than one-quarter of its 531 pages to Mr. Xi’s policies and achievements.

Mr. Xi has said that the post-Mao period shouldn’t be used to repudiate the Mao era, suggesting that China’s past struggles set the stage for its current success.

“Official party history tells people—from leaders to cadres to ordinary citizens—how they should act, how they should talk in public and what they should avoid,” said Timothy Cheek, director of the University of British Columbia’s Institute for Asian Research.

The history academy’s revisionism hasn’t always gone over well with the public. In December, its Weibo account drew wide criticism for an essay, since taken down, that challenged popular condemnation of Mao’s “Down to the Countryside Movement,” which forced millions of urban young people to live and work in rural villages.

The essay described the movement as “a great achievement that advanced the development of society,” according to copies that have been republished online. In that respect, it echoed official portrayals of the seven years Mr. Xi spent as a “rusticated youth” in the countryside as a transformative experience that taught him to serve the people.

Some Chinese historians say the academy is twisting history to serve politics. “They aren’t following an academic path,” said a prominent history professor in Beijing, who said he declined the academy’s invitation to collaborate on a project. “These people are doing this to suck up and win promotion.”

In April, Mr. Xi visited a memorial to a 1934 battle that took place during the “Long March,” a military retreat over thousands of miles by Communist Party troops that was later celebrated as a strategic triumph that helped Mao secure power. Mr. Xi urged his compatriots to emulate the undying faith and self-sacrifice shown by the Red Army.

When confronting challenges, domestic and foreign, in pursuit of China’s rejuvenation, he said, “We must have such conviction in our inevitable victory.”

Write to Chun Han Wong at chunhan.wong@wsj.com and Keith Zhai at keith.zhai@wsj.com