Peng was featured prominently in Sunday's Chinese media coverage of her husband President Xi Jinping in Russia on his first state visit since he assumed the presidency earlier in March.
A celebrated performer on state television, Peng watched song-and-dance routines at a performing arts school on Saturday, but did not join in as some media reports had suggested she might.
The couple arrived in Tanzania later on Sunday, and their trip also includes stops in South Africa and Congo.
An internationally popular first lady could help soften China's sometimes abrasive international image and mark a victory in its so-far unsuccessful struggle to win over global public opinion.
At the same time, she could boost the popularity of the country's new leadership at a time when citizens are feeling increasingly alienated and are fed up with the ruling class's corruption and regal airs.
In recent years, the wives of China's top officials have traditionally gone almost unseen at home and attracted little attention while accompanying their husbands on state visits.
Chinese President Xi Jinping's wife Peng Liyuan after arriving at the government airport Vnukovo II, outside Moscow. AP Photo
That was in part a negative reaction to Mao Zedong's wife, Jiang Qing, who was widely despised and later imprisoned for her role as leader of the radical Gang of Four, which mercilessly persecuted political opponents during the chaotic 1966-76 Cultural Revolution.
Recently retired Premier Wen Jiabao's wife, Zhang Peili, became known for her role in the country's gem trade and was never seen in public with her husband.
Meanwhile, Bo Xilai, one of China's most ambitious politicians, was brought down in spectacular style last year following his wife's involvement in the murder of a British businessman, setting off the country's nastiest political scandal in years.
Women in general wield relatively little power at the top of the Chinese power structure, with just two sitting on the ruling Communist Party's 25-member decision-making Politburo.
Peng's emerging high profile appears to be an extension of Xi's own confidence as he consolidates his control on power and presses a more assertive role for China in global affairs, said Steve Tsang, director of the China Policy Institute at Britain's University of Nottingham.
Her training as a singer and stage performer offers the perfect preparation for such a role, he said.
"Peng is projecting a certain poise and confidence that Xi himself is carrying and he doesn't need to worry about what other (politicians) might think of her," Tsang said.
Peng's image was splashed across Chinese newspapers over the weekend, shown descending arm-in-arm with Xi as they descended from their aircraft after arriving in Moscow on Friday.
Her visit to the arts school was carried by state broadcaster CCTV on its main Sunday news broadcast and reported in national newspapers.
The popular Beijing News tabloid ran a full page of items on Peng's appearances on Sunday, alongside a photo of her arriving at a speech Xi gave Saturday, dressed in an elegant Chinese-style silk tunic and skirt.
"In her role as first lady on this visit abroad, Peng Liyuan is exhibiting China's soft power," the paper quoted Wang Fan, head the Institute of International Relations at China Foreign Affairs University, as saying.
Tanzania's First Lady Salma Kikwete, Chinese President Xi Jinping, Tanzanian President Jakaya Kikwete and the First Lady of China Peng Liyuan pose at State House in Dar Es Salaam, Tanzania. AFP
"As a singer and artist and a long-term advocate for poverty relief and other causes, Peng has an excellent public image."
Much of the coverage focused on her personal style, with a report on the mass-market sina.com website noting with satisfaction that the black leather clutch she paired with the outfit was made to order by a Chinese firm in the southwestern city of Chengdu, a flattering contrast with prominent Chinese female politicians scorned publicly for appearing decked head to toe in foreign designer brands.
"In practical terms, this is an important show of support for China's domestic industries, but in the larger sense, it should raise national self-respect and confidence," read a posting on China's popular Weibo microblogging service left by Lin Zhibo, Gansu provincial bureau chief of the Communist Party's flagship newspaper, People's Daily.
Chen Li, a real estate agent from the central city of Changsha, said Peng was well-known for her modest ways and calm, dignified manner.
Chinese First Lady, Madame Peng Liyuan at Julius Nyerere International Airport in Dar es Salaam. AP
"She's known to be elegant and fashionable, but she's also very low-key and doesn't seem arrogant in the way that you usually associate with the wives of top leaders," Chen said.
Peng, 50, largely retired from public life after Xi was made China's leader-in-waiting in 2007, but in recent years has won new acclaim as an ambassador for the World Health Organization.
Among the issues she has worked on are tuberculosis and HIV/AIDS — diseases that still carry considerable social stigma in China.
She also made headlines last year by appearing alongside Microsoft co-founder Bill Gates as part of a campaign to discourage smoking, a high-profile cause in a country where about two-thirds of men smoke.
Peng is Xi's second wife, and the two are separated in age by almost a decade.
While Xi's father was a leading revolutionary and former vice-premier, making his son a member of the "red aristocracy," Peng comes from relatively humble origins and joined the People's Liberation Army when she was 18. The couple has one daughter, a student at Harvard who remains out of the limelight.
While sometimes described as a folk singer, Peng holds the rank of PLA major general and is best known for her stirring renditions of patriotic odes, often while wearing full dress uniform.
Although her rank is largely honorary, her military status could lead to awkward questions, said University of Nottingham's Tsang.
"Sooner or later, someone is going to ask whether that's completely normal, even if she doesn't have any real military or political ambitions," Tsang said.