Jurors found Chicago businessman Tahawwur Rana guilty of material support for the Lashkar-e-Taiba terrorism group and for his role in planning a revenge attack on a Danish newspaper that published cartoons of the prophet Muhammed.
The jury did not, however, convict him for his alleged role in the Mumbai terror attacks of 2008, which was the most serious of the charges.
Prosecutors allege Rana aided David Headley, who pleaded guilty to scouting sites for the attack that left more than 160 people dead.
Headley testified as the government's star witness the trial, saying he took orders from Pakistani intelligence and a Pakistani militant organization.
The case is being closely watched amid suspicions that Pakistan's government may have been protecting Osama bin Laden before the al-Qaida leader's killing by U.S. forces. Pakistan denies the allegations.