The decision by the eight-person jury came at the end of the third full day of deliberations.
The jury also found that Apple had infringed on one of Samsung's patents in creating the iPhone 4 and 5. The jury awarded Samsung $158,400. Samsung had sought $6 million.
Both companies will now try to urge the judge to remove the other's products from store shelves in the United States.
The verdict marked the latest intellectual property battle between the world's top two smartphone makers. Apple and Samsung have sued each other in courts around the world.
"Samsung willfully stole our ideas and copied our products," Apple spokeswoman Kristin Huguet said. "We are fighting to defend the hard work that goes into beloved products like the iPhone, which our employees devote their lives to designing and delivering for our customers."
Samsung did not provide any comment yet.
Samsung lawyers made Google a central focus of their defense, caliming that Google was Apple's real target.