Rubio, who co-chairs the Congressional-Executive Commission on China (CECC), said that "human rights and the rule of law have suffered a devastating blow" since Xi assumed the presidency.
"By nearly every possible measure, China today is more repressive and more brutal," he said.
"Millions of Chinese people yearn for the same basic rights that we as Americans enjoy, but their aspirations have been met with intimidation, imprisonment, torture and even death."
The CECC, created in 2000, monitors and reports on human rights and the development of the rule of law in China.
In the latest report, the bipartisan commission called for a top-down reformulation of U.S. human rights diplomacy with Beijing.
Obama criticized for not pushing Beijing on human rights
Human rights have taken something of a back foot in recent years when it comes to Sino-U.S. relations.
President Barack Obama has been criticised by Republicans for not doing enough to pressure Beijing on the issue.
During Xi's recent state visit to Washington, Obama pointedly raised the issue during a joint news conference.
"We recognize that there are real differences there, and President Xi shared his views in terms of how he can move forward in a step-by-step way that preserves Chinese unity," he said.
Obama also mentioned the name of Tibet's spiritual leader -- who is regarded by China as a separatist.
"Even as we recognize Tibet is part of the People's Republic of China, we continue to encourage Chinese authorities to preserve the religious and cultural identity of the Tibetan people, and to engage the Dalai Lama or his representatives," he said.
Xi said he was willing to have a human rights dialogue with the United States, but as is customary with Chinese leaders, he pointed out that the concept of human rights was seen differently in Beijing.
"We must recognize that countries have different historical processes and realities, that we need to respect people of all countries in the rights to choose their own development independently," he said.