Wei Zhongping and Liu Ping, associated with the New Citizens' Movement, were given six-and-a-half years in jail. A third activist, Li Sihua, received a shorter sentence.
Rights group Amnesty International said the charges were "preposterous".
China's leaders are running a crackdown on corruption, but refuse to tolerate grassroots groups with similar aims.
The three activists were detained after taking photographs with banners urging officials to disclose their assets.
They were put on trial in a high-security court in Xinyu, Jiangxi province, late last year.
At the time, defence lawyers complained of serious procedural problems and said they were not confident of the outcome.
The three were convicted of the broad charge of "creating a disturbance".
Liu and Wei were convicted of other charges, which Amnesty said included "gathering a crowd to disrupt order in a public place" and "using an evil cult to undermine law enforcement".
"The charges against these activists were preposterous from the very beginning," said Amnesty's William Nee.
The UK-based rights group described them as "prisoners of conscience" and called for their immediate release.
Chinese leader Xi Jinping launched an anti-corruption drive when he took over in 2012.
But he has also overseen the broadest crackdown on grassroots activism that China has seen in recent years.
Several activists in the New Citizens' Movement, which calls for more democracy and government transparency, have been detained.
In July last year, prominent lawyer Xu Zhiyong, one of the founders of the movement, was detained on suspicion of having "gathered crowds to disrupt public order".
He was eventually jailed for four years in January.
Three Chinese anti-corruption activists have been given lengthy jail terms for urging officials to disclose wealth.