Thankfully, the accident wasn't serious and was described by the gossip column as more of a fender-bender than anything else.
Still, an ambulance was called to the scene on New York's Long Island "as a precaution," reports Page Six.
The Oscar winner, 41, and his Dutch model girlfriend, 24, were unharmed after the car they were traveling in -- which reportedly belonged to one of Leo's friends -- got rear-ended by a Mini Cooper.
A source close to the actor told Page Six, "[Leo and Nina] got rear-ended, but everyone is doing fine."
After briefly dating in 2014, Leo and the Sports Illustrated Swimsuit Issue stunner rekindled their romance in June 2016.
All summer long, they've been spotted together everywhere from Cannes, France, and New York City to the Hamptons and Malibu, California.
Through the years, the actor -- a notorious modelizer -- has famously been linked to a seemingly endless stream of beauties including Helena Christensen, Amber Valletta, Gisele Bundchen, Bar Refaeli, Erin Heatherton, Toni Garrn, Kelly Rohrbach, Chelsey Weimar and Roxy Horner, among others.
"The truth is, you can't predict marriage," he told Parade in January 2016. "You can't plan it. It's just going to happen when it happens."