The verdict came shortly after closing arguments finished Wednesday in the misdemeanor case.
The 30-year-old Simms was arrested at a sobriety checkpoint early on July 1.
A police officer stated that Simms was "zombie"-like and said he'd been smoking marijuana. His lawyer said the officer misunderstood Simms when he said a passenger had been smoking the drug.
The passenger, Charles Granatell, testified Tuesday that he smoked pot while Simms made a brief stop at another friend's birthday party. Granatell said he'd never seen Simms smoke marijuana since they met roughly 12 years ago.
Simms started his career with the Tampa Bay Buccaneers in 2003. His father is former New York Giants quarterback Phil Simms.