The 26-year-old heartthrob narrowly escaped a fine after being photographed cycling through Adelaide without the requisite head gear.
Pattinson, who is currently filming a new movie set in the Australian outback, was seen riding along the River Torrens wearing only a backwards baseball cap.
Under South Australian law, riders must wear “an approved bicycle helmet that is properly adjusted and securely fastened''.
After the incriminating photo appeared in the Adelaide Advertiser earlier this week, local police officers spoke with the star's management team and warned them that next time he would be receiving a fine.
A South Australian police spokesman told The Telegraph that the star had been "cautioned" and that officers were "confident Mr Pattinson is now well aware" of the local laws.
Pattinson is currently filming The Rover, a futuristic western set in the Flinders Ranges in the Australian desert.
He plays an injured gang member in the film, which is being directed by David Michod and co-stars Guy Pearce.