They campaigned for government officials to declare their wealth but join more than a dozen people detained in recent months for daring to organise anti-corruption protests.
Their jailing, the culmination of a high-profile trial, underscores the ruling Chinese Communist Party’s determination not to permit dissent.
Rights groups say the crackdown on the group also throws into sharp relief the limits of Mr Xi’s anti-corruption initiative.
Despite a few pilot schemes for low-level officials to disclose their assets, any public discussion of the wealth of senior leaders remains strictly off limits.
Corruption – specifically the abuse of political power for personal gain – oils the wheels of China’s government and probes into party elites have revealed billions of pounds in undisclosed assets, often held by friends or relatives of officials.
Two of the activists, Liu Ping and Wei Zhongping, were sentenced to six-and-a-half years in prison for allegedly using a cult to undermine law enforcement, organise public disorder and provoke disputes “by picking quarrels”.
“It isn’t fair, it isn’t just,” said Si Weijiang, Liu’s lawyer.
“The laws can just be bent however [the government] wants in politicised cases.”
Another activist, Li Sihua, was sentenced to three years in prison, also for alleged trouble-making.
The sentences were handed down yesterday by a court in the poor central province of Jiangxi.
Amnesty International called the charges “preposterous”.
“Having a small private gathering and holding a banner in a lobby entrance demanding financial transparency from officials should not in any way constitute ‘picking quarrels’ and ‘illegal assembly’,” said William Nee, a China researcher for the human rights group.
Mr Si said he did not believe any appeal would be successful or have any meaning.
The activists, encouraged by Mr Xi’s anti-corruption campaign, took photographs of themselves holding banners and placards that read: “Strongly urge officials to disclose their assets” and “Xi Jinping, immediately end dictatorship”.
The photos were widely circulated online.
The activists were part of a group called the New Citizens Movement, which advocates that officials disclose their wealth and aims to promote change within the existing state system.
Its founder, Xu Zhiyong, was sentenced in January to four years in prison, sparking criticism from the European Union, United States and rights groups.
“This is a crazy retaliation, a shameless retaliation, which has no connection with the law, the legal system or rule of law,” the New Citizens Movement said in an online statement.
“This is not just a retaliation against Liu Ping, Wei Zhongping and Li Sihua but dishonours the rights of citizens.”
Lawyer Pu Zhiqiang, who had represented members of the New Citizens Movement, was detained last month after he attended a meeting in a private home to commemorate the anniversary of the bloody suppression of pro-democracy protests at Tiananmen Square in 1989.