The building is routinely lit with different colors to mark holidays and big events, but opponents questioned whether it's right to commemorate a sensitive political issue, particularly when China has such a poor human rights record.
About 20 supporters of Tibet, which China has ruled since shortly after communists took over in 1949, protested outside the building during a ceremonial lighting of a scale model inside the lobby. They chanted "No to China's empire; free Tibet now," and held signs reading, "Empire State Building celebrating 60 years of China's oppression."
Lhadon Tethong, executive director of Students for a Free Tibet, called the lighting "outright, blatant approval for a communist totalitarian system."
"It's a great public relations coup for the Chinese state," Tethong said as tourists gawked at the protesters. "But on the other hand, it's sure to backfire because the American public and the global public will speak against it."
At the lobby ceremony, building manager Joseph Bellina called the lights a high honor and said he was proud of the relationship between "our countries and our people."
Chinese Consul General Peng Keyu, who pulled the switch on the glass-encased model, said he was "honored and delighted."
He said China's reforms of the past 30 years have led to greater openness and "tremendous change."
Keyu and Bellina didn't address critics and declined to answer questions.
Journalist and blogger Marc Masferrer questioned legitimizing a government that continues to repress its citizens' freedoms, including their access to media and the Internet.
"I don't think one of our great landmarks should be turned into a platform to honor a regime and a system responsible for as much tragedy and all the other things that come with a repressive system," he told The Associated Press.
Masferrer pointed out that this year is also the 20th anniversary of the violently crushed student-led movement in Beijing's Tiananmen Square. The People's Liberation Army is believed to have killed hundreds, possibly thousands, of protesters.
Politicians united in their disdain.
Rep. Anthony Weiner, a New York Democrat, said the lights should not be used to pay tribute to what he called "an oppressive regime" with a "shameful history on human rights."
Rep. Peter King, a New York Republican, said it was "a sad day for New York."
"I am strongly opposed to it or any commemoration of the Communist Chinese revolution. It's one thing to acknowledge the government; it's totally immoral to honor it."
The lights atop the building, which is owned by W&H Properties, are often are changed. For example, Italian colors — red, white and green — commemorate Columbus Day, while green, white and orange are displayed for the India Day parade.
For the Chinese anniversary, the lights were to remain on through early Thursday.
Associated Press writer Deepti Hajela contributed to this report.