Annie George, 40, who owns the Llenroc Mansion home near New York state's capital, Albany, was found guilty of one count of harbouring an illegal alien. She was found not guilty of the stiffer charge of harbouring an illegal alien for financial gain.
Ms George was accused of keeping Valsamma Mathai from Kerala as a 'slave' in her mansion.
The 12-member jury announced the unanimous decision after a day and a half of deliberations, The Saratogian, a local newspaper reported.
Prosecutors claim that Ms Mathai was used as a domestic, cook and babysitter by the family for up to 17 hours a day, seven days a week from October 2005 through May 2011. The government claimed her agreed-upon salary was USD 1,000 per month.
Ms Mathai said she was paid only USD 26,000, much of which she sent to her family in India. But because the jury didn't find George guilty of keeping Mathai for financial gain, the original charge, she won't be liable for the wages, said George's lawyer, Mark Sacco.
Ms George faces up to five years in prison and is scheduled to be sentenced July 9. She could also receive up to USD 250,000 in fines and lose her ownership stake in the mansion.
She is currently free on bail.
Neither Ms George nor her family and friends who were in the courtroom showed any emotion as the verdict was read.
Ms Mathai was not present in court but testified earlier this week that she felt she was a prisoner in the mansion.
Ms George had said she didn't know Ms Mathai was in the US illegally. She also said she didn't mistreat her during the 5 1/2 years she worked in her home.
The trial, which began Monday, centered on the May 3, 2011, removal of Ms Mathai by agents of the US Department of Homeland Security Investigations.
Ms George was arrested in February 2012 for harbouring her for 5-1/2 years at three different homes and using her as a servant for personal gain.
Ms George's husband, Mathai Kolath George, and her eldest son were killed in a plane crash in 2009.
After the verdict, Sacco said his client was devastated by the verdict. He said Ms George was focused on taking care of her five children and feels somewhat vindicated from the charge she was mistreating someone.
"We're disappointed," Sacco said.
In a statement, US Attorney Richard Hartunian said, "This case demonstrates our commitment to investigate and prosecute those who harbor illegal aliens."