"The imprisonment of Huang Qi underscores China's continued repression of human rights and fundamental freedoms, including free speech," the press statement said.
The Mianyang Intermediate People's Court in the central province of Sichuan on Monday announced that Huang was sentenced on charges of leaking state secrets and illegally providing state secrets to foreign entities, the Efe news reported.
As part of the sentence, Huang was also stripped of his political rights for four years and ordered to pay a 20,000-yuan ($2,900) fine.
"Huang has been honoured multiple times by Reporters Without Borders (RSF) for his courage in exposing corruption and human rights violations in China through his Web site, 64 Tianwang," the State Department said.
The 56-year-old journalist, whose website has served as a platform for dissident voices, has been arrested many times - most recently in 2016 - and spent years in prison on charges of inciting subversion and illegal possession of the state secrets.
"We urge the Chinese government to uphold its international commitments related to fair trial guarantees and the rule of law," the State Department statement said. "We call on China to immediately release Huang, and to allow him access to his family, medical care and legal counsel as soon as possible."
Washington also urged the Chinese government to "end undue restrictions on the freedom of movement of his family and those who assisted him."
London-based human rights watchdog Amnesty International criticised the fact that family members of the activist, who suffers from chronic poor health, had not been informed of the latest sentence.
AI and other human rights groups in the past have alleged that Huang has been tortured during his time in custody, a common complaint by activists, journalists and human rights lawyers who have been held in Chinese detention centres.
In December, the United Nations expressed serious concerns about the deteriorating state of Huang's health and urged the Chinese government to release him immediately.
According to human rights experts cited then by the Office of the UN High Commissioner for Human Rights, Huang suffers from "high blood pressure, heart disease, chronic kidney condition and hydrocephalus".
"Without the required medical treatment, Huang's health may continue to deteriorate to a fatal point," the experts said.
The RSF issued a statement on Monday urging Chinese President Xi Jinping to pardon Huang.
Noting that his latest sentence was preceded by a two-year detention and a closed trial on January 14, the Paris-based media watchdog said Huang "is in reality punished for his commitment to reporting human rights violations by certain Chinese officials".
"This decision is equivalent to a death sentence, considering Huang Qi's health has already deteriorated from a decade spent in harsh confinement," RSF Secretary-General Christophe Deloire said.
( With inputs from IANS )