Maloney, 14, was hit around midnight at the Middle Country Road intersection.
Police say she was crossing the road with a friend, darted out into the westbound lane and didn't see the oncoming vehicle.
The driver attempted to swerve but was unable to avoid hitting her.
Maloney was listed in critical condition at Stony Brook University Hospital on Monday afternoon. No details about her injuries were released.
The driver of the SUV and his passenger were not injured.
The vehicle was impounded for a safety check.
Police ask anyone with information about the crash to call the Fourth Squad at 631 854-8452.