Hashmi, a Pakistan-born US citizen, had faced up to 70 years in prison if convicted of four criminal counts.
"We were terribly concerned our man was throwing away his life," said David Ruhnke, Hashmi's lawyer.
"He's made the best deal that was available under the circumstances."
Three years in solitary
Hashmi told Loretta Preska, a US district judge, that between January 2004 and May 2006, he helped Junaid Babar, a friend from Queens, New York, transport the protective equipment to fighters.
Hashmi, a student, lent Babar $300 and stored the materials in his apartment. He was arrested at Heathrow airport in Britain in June 2006 under an extradition request by US authorities.
He arrived in the United States in May 2007, having spent almost a year in detention.
Family, friends and rights groups say the US government prosecuted Hashimi because he was outspoken against US policies in the Middle East.
Rights groups have also been critical of Hashmi's conditions of imprisonment, where for almost three years he has been in solitary confinement with 23-hour-a-day lockdowns, constant video surveillance and almost no visitors.
Hashmi will be sentenced on June 7.