Photos showed Yee, who has been jailed twice in native Singapore for critical views on race and religion, leaving a US immigration facility in downtown Chicago with a friend and his belongings stuffed in a plastic bag. A photo posted on his Facebook page
was captioned: "Amos Yee is now a free man."
"I'm kind of stunned right now," he told the Chicago Tribune.
"It's very surreal."
Lee came to the United States in December under the visa waiver program and requested asylum
, which was granted in March by Immigration Judge Samuel Cole.
Cole described Yee as a "young political dissident," saying "his prosecution, detention and general maltreatment at the hands of Singapore authorities constitute persecution on account of Yee's political opinions."
The Department of Homeland Security, which opposed his asylum application, appealed the judge's decision, however the Board of Immigration Appeals said
they agreed with Cole's findings.
Singapore's government criticized the March decision
, saying: "It is the prerogative of the US to take in such people who engage in hate speech."
Trouble with authorities in Singapore
In July 2015, Yee was detained for 53 days after he posted a YouTube tirade praising the death of Singapore's first Prime Minister, Lee Kuan Yew. Yee described the politician as "totalitarian" and compared him unfavorably to Jesus and Mao Zedong.
In another incident in September last year, Yee was sentenced to six weeks in prison for controversial religious posts that he wrote and shared on social media.
In that case, a court found him guilty of eight charges: six related to "wounding religious feelings" and two for his failure to turn up at a police station when summoned.
"He has, on several occasions, deliberately elected to do harm by using offensive and insulting words and profane gestures to hurt the feelings of Christians and Muslims," principal district judge Ong Hian Sun wrote in court documents obtained by CNN at the time.
The prosperous Southeast Asian city-state of Singapore -- with an estimated population of 5.7 million -- is ethnically and religiously diverse.
Critics have said his arrest and subsequent detention highlighted the restrictions on free speech in Singapore, where criticism of leaders and the government is frowned upon.