HONG KONG — A court in southern China sentenced a blogger to four years in prison for his work documenting mass unrest around the country.

The blogger, Lu Yuyu, was convicted Thursday of “picking quarrels and provoking trouble” by a court in the city of Dali in Yunnan Province, said Wang Zongyue, one of his lawyers.

The charge of picking quarrels is often used to prosecute cases of political dissent and in recent years has expanded to cover online activities.

Mr. Lu, a migrant worker from Guizhou Province in southwestern China, began using the internet to research and publish information about some of the tens of thousands of strikes, protests and riots across China each year.

Such incidents are usually ignored by the Chinese news media and are difficult to cover for foreign journalists based in major cities like Beijing and Shanghai. In contrast, Mr. Lu and his girlfriend, Li Tingyu, were able to research and share news of large-scale protests, sometimes more than one each day.

Strikes and other labor unrest were a main focus of their work. But they also documented protests over land confiscation, pollution and local corruption.

They called their work “Not News.” While many of their sites have been taken down, their reporting remains on a Tumblr site with their oft-used handle Wickedonna. The postings show how they used Chinese social media services, particularly Weibo, to collect images of incidents before they were erased by online censors.

The police in Dali detained the couple last year. Ms. Li went to trial in April and was subsequently released, but the verdict in her case was never made public, according to Chinese Human Rights Defenders, a watchdog group. Mr. Lu said she had been given a suspended sentence but offered no details, according to Mr. Wang, the lawyer.

The couple’s work was used by journalists and labor researchers trying to gauge the extent of strikes around China and to learn more about particularly noteworthy incidents. Last year they were awarded a Reporters Without Borders-TV5 Monde Press Freedom Prize.

“Lu Yuyu and Li Tingyu worked tirelessly to document the everyday collective actions of Chinese citizens,” Keegan Elmer, a researcher for China Labor Bulletin, a Hong Kong-based nonprofit, said by email. “Their project should be commended, not condemned, and advocates of freedom of the press everywhere owe them a tremendous debt of gratitude.”

Silencing their reporting “will not change the stark reality of the tens of thousands of incidents that occur each year throughout the country, as their records clearly showed,” he added.

Mr. Lu has appealed his conviction, Mr. Wang said. “We think Lu is innocent and didn’t expect him to be sentenced for four years at all,” he added.