Officials said 26-year-old Kandice Gillard was camping overnight with her brother for his birthday at the Little River.
The brother woke up Saturday morning and he told officials his sister had disappeared, leaving the wheelchair behind.
Johnston County officials found Gillard's body down the river, about 100 yards from the campsite.
The body was sent to Chapel Hill for an autopsy to determine the cause of death.
Authorities said they do not suspect foul play, but the investigation is ongoing.