The grim figures come a week after grief and public anger erupted over the death of a whistleblowing doctor who had been reprimanded and silenced by police after raising the alarm about the virus in December.
Elsewhere, Japan confirmed another case, a Japanese man in his 70s, a day after it reported its first death from the virus. Those deaths were reported in the Philippines and Japan.
Hubei province is now including cases based on a physician's diagnosis before they have been confirmed by lab tests.
Officials said the epidemic is still intensely centered in China.
A wave of anger and grief flooded Chinese social media site Weibo when news of Dr Li's death broke.
Under criticism over the handling of the crisis, the Communist Party sacked two top-ranking officials in Hubei, and replaced them with senior cadres with security backgrounds.
The new cases include 3,095 patients that are "clinically diagnosed" after the province changed its counting method.
The revision added almost 15,000 patients to Hubei's count in a single day, with officials explaining that past cases were included.
China's coronavirus outbreak showed no sign of peaking with health authorities on Friday reporting more than 5,000 new cases, while passengers on a cruise ship blocked from five countries due to virus fears finally disembarked in Cambodia.
The sharp one-day increase "does not represent a significant change in the trajectory of the outbreak", said Michael Ryan, head of WHO's health emergencies program.
"So, in other words, in Hubei province only, a trained medical professional can now classify a suspected case of COVID-19 as a clinically-confirmed case on the basis of chest imaging, rather than having to have a laboratory confirmation".
"There have been some backlogs in testing and this is also going to help in ensuring that people get adequate care", Ryan said.
The death toll from the coronavirus has well passed the roughly 775 people who died from the SARS epidemic of the early 2000s.
No vaccine exists for the coronavirus now, but public health officials urged the public to take precautionary measures similar to those taken during flu season, including washing one's hands with soap and warm water for at least 20 seconds, covering coughs and sneezes and staying home if one is sick.
Some cities in Hubei tightened restrictions this week, sealing off neighborhoods in what they liken to "war-time" measures.
Local authorities have struggled to provide protective equipment such as respiratory masks, goggles and protective suits in hospitals in the area.
World Health Organization chief Tedros Adhanom Ghebreyesus greeted news of the slowdown with caution Wednesday, saying the outbreak "could still go in any direction".
"Investors will surely avoid Asia for the time being and will shift funds to the USA, geographically the most separated from the region", said Norihiro Fujito, chief investment strategist at Mitsubishi UFJ Morgan Stanley Securities.
Japan is one of the worst affected of more than two dozen countries and territories outside mainland China that have seen hundreds of infections.