Lynne Stewart, 67, was convicted in February 2005 of lying to the government and conspiring with her client, Sheikh Omar Abdul Rahman, to convey messages to his militant disciples in Egypt, inciting them to violence.
Her sentencing had been delayed while the veteran attorney and grandmother underwent treatment for breast cancer.
In a letter to Judge John Koeltl before her sentencing on Monday, Stewart insisted she was a well-intentioned lawyer who had made a lapse in judgement. She faces up to 30 years in jail if convicted.
"I am not a traitor. The government's characterisation of me and what occurred is inaccurate and untrue. It takes unfair advantage of the climate of urgency and hysteria that followed 911," she wrote, referring to the September 11, 2001 attacks on New York and Washington.
Abdul Rahman was jailed for life after being convicted in 1995 of conspiring to blow up New York landmarks and assassinate Egyptian President Hosni Mubarak.
Stewart's two co-defendants, US postal worker Ahmed Sattar and Arabic translator Mohammed Yousry were also due to be sentenced on Monday.
When her verdict was handed down last year, a tearful Stewart told reporters outside the courthouse: "I hope this will be a wake up call to all citizens... You can't lock up all the lawyers. I will fight on."
Ever since she was charged, Stewart has insisted she was being unfairly targeted for her unorthodox choice of clients over a 30-year career that has seen her represent mobsters and political radicals.
US Attorney General Alberto Gonzales said at the time the verdict was an "important step" in the Department of Justice's "war on terror".
Giving testimony during the trial, Stewart had insisted that she neither abetted nor endorsed the concept of Islamic holy war held by Abdul Rahman.
Prosecutors held that between 1997 and 2002, Stewart and her co-defendants helped Abdul Rahman pass messages to his followers in violation of government restrictions on his right to communicate with the outside world.
In particular, the prosecutors said, Abdul Rahman used the three defendants to exhort his militant group to break a cease-fire with the Egyptian government.

Copyright AFP (Agence France-Presse), 2006