Xu was charged with "gathering a crowd to disturb order in a public space" for his role in organizing protests in 2012 and 2013 to advocate for rural children's education rights and government transparency.
Amnesty International China researcher William Nee said, "Today's ruling makes a mockery of justice as the decision was a foregone conclusion ... Instead of upholding freedom of expression and assembly, the court opted yet again to trample all over these fundamental rights."
The U.S. Department of State expressed dismay following the court's decision.
"The United States is deeply disappointed that a Chinese appellate court has upheld the four-year prison sentence for prominent legal scholar and rights advocate Xu Zhiyong as retribution for his public campaign to expose official corruption and for the peaceful expression of his views.
"As the United States has previously stated, we remain deeply concerned that the prosecution of Xu and others is part of a deepening pattern of arrests and detentions of public interest lawyers, Internet activists, labor activists, journalists, religious leaders and others who peacefully challenge official Chinese policies and actions.
"We call on Chinese authorities to release Xu and other political prisoners immediately, remove restrictions on their freedom of movement, and guarantee them the protections and freedoms to which they are entitled under China's international human rights commitments."