Rumours were circulating about the whereabouts of the president amid China's coronavirus epidemic which has seen 636 deaths so far on the country's mainland.
The state leader hadn't been seen in several days with Xi missing his regularly scheduled media appearances – odd behaviour for a leader who dominates the Chinese press.
Xi typically appears on CCTV's main news programme and the front page of the People's Daily almost every day, as both are run by the ruling Communist Party.
The newspaper in particular often devotes entire front page spreads to photos of the president meeting dignitaries and conducting normal business.
He was absent from Chinese media for several days, sparking rumours online he had effectively quarantined himself or allowing other political figures to take the fall for the crisis.
But he resurfaced today as he appeared in the state media.
Xi assured US President Donald Trump that China was doing all it can to contain a new coronavirus that has killed almost 640 people, including a doctor who sounded the alarm only to be threatened by police.
China was gradually achieving results and was confident it could defeat the epidemic with no long-term consequences for economic development, Xi told his US counterpart in a telephone call, according to state television.
The phone call to the White House comes as China accused it of scaremongering over the epidemic.
Xi had earlier declared a "people's war" on the virus, saying China had responded with all its strength and "the most thorough and strict prevention and control measures", state media said.
The rallying cry came amid an outpouring of grief and anger on social media over the death of ophthalmologist Li Wenliang.
Li, 34, was one of eight people reprimanded by police in the central city of Wuhan, the epicentre of the contagion, last month for spreading "illegal and false" information about the flu-like virus.
His social media messages warning of a new "SARS-like" coronavirus – a reference to Severe Acute Respiratory Syndrome (SARS) which originated in China and killed almost 800 people around the world in 2002-2003 – triggered the wrath of police.
China was accused of trying to cover up SARS.
Li was forced to sign a letter on January 3 saying he had "severely disrupted social order" and was threatened with charges.
"We deeply mourn the death of Wuhan doctor Li Wenliang... After all-effort rescue, Li passed away on 2.58 am," the ruling Communist Party's People's Daily said on Twitter.
Many social media users described Li as a hero, accusing authorities of incompetence in the early stages of an outbreak that has now claimed more than 400 lives in Wuhan.
"Light a candle and pay tribute to the hero," one person posted on the Weibo platform.
Some media outlets described Li as a hero "willing to speak the truth" but there were signs that discussion of his death was being censored.