Deena Gilbey, 39, of Chatham was left in a legal limbo when her husband, Paul, was killed while working as a trader for EuroBrokers on the 84th floor of the center's south tower.
He is credited with helping evacuate co-workers and then staying behind to rescue others.
His work visa, however, applied to his wife only while he was alive.
Ordinarily, foreign nationals applying for residency wait up to 60 days for approval following their interviews, in order to give federal agencies time to conduct background checks.
But Kerry Gill, a spokesman for the Immigration and Naturalization Service in Newark, said Gilbey was issued her green card without delay because the necessary background checks had already been conducted under special legislation on her behalf that was introduced in December but never passed.
"Mrs. Gilbey extends her thanks and appreciation to the good and kind people of the United States ... and to those at the INS, who, after nearly a year of doubt, gave Deena and her children back a piece of their lives," Michael Wildes, Gilbey's lawyer, said in a statement.
Gilbey and her two children live in Chatham, New Jersey. Mason, 7, and Max, 4, are American citizens by virtue of having been born in the United States.
Paul Gilbey did not have a green card. He had applied for the residency permit in 1994, but had to restart the application process when he changed jobs.
Deena Gilbey, who came to the United States 10 years ago with her husband, was awarded the green card under the USA Patriot Act, a law passed in the aftermath of the attacks that allows foreign-born spouses and children of Sept. 11 victims to apply for residency.
Gilbey attracted widespread attention to her case in numerous interviews with news organizations in which she said the Immigration and Naturalization Service had threatened to deport her.
"When I asked 'What will happen to me?' they responded, 'You will be arrested and deported,'" Gilbey was quoted as saying by The New York Post on Monday.
Wildes said Thursday "finally, the government rose to the occasion."
But, he added, the agency only granted her residency following an hour-long, videotaped interview in Newark after he pointed out that the CIA had already completed the background check.
Wildes thanked news organizations and the public for putting what he said was pressure on the INS to let Gilbey stay in this country indefinitely. He said Gilbey was not available for comment.
The agency denied ever threatening to deport Gilbey, and insisted it pointed out to her that she was eligible to apply for residency under a provision of the U.S.A. Patriot Act, approved in October.
The INS also denied its handling of the case was influenced by media attention.
"The decision was based solely on the content of her application and her eligibility," Gill said.
Gilbey has been getting by with help from charity organizations such as the United Way of America, but the green card will allow her to work and travel, Wildes said.