Police Capt. Robert Regalbuto said Abiah Jones of Pleasantville was with her classmates from Pleasant Tech Academy when she fell from the ride at 9:30 a.m. PST. She fell from the upper half of the ride, about 100 feet.
She was driven to a nearby hospital, where she was pronounced dead about 45 minutes later.
The 156-foot-tall Ferris wheel is among rides at Morey's Mariner's Landing Pier.
The popular park was packed with school children attending a special school-related promotional day called "Education Extravaganza."
Morey's said in a statement the cause was being investigated. A Wildwood police statement said the cause of the fall remains unknown. Both Morey's and police said the problem did not appear to be mechanical.
Police took photographs of various passenger carts on the Ferris wheel, part of which was covered in white sheets, and were looking for witnesses to the fall.
The Ferris wheel, which was built in 1985, most recently passed an inspection on March 17, according to the New Jersey Department of Community Affairs.
According to a 2010 report from the National Safety Council, the estimated number of amusement ride-related injuries on fixed-site rides nationwide was 1,086 or 0.6 per million patron rides.
After closing the Ferris wheel and a few others nearby but keeping the rest of the park open throughout the afternoon, the amusement park's owners decided around 4 p.m. to close the entire park for the remainder of the night. It was due to reopen Saturday morning.
"The Morey staff and family offer our thoughts and prayers to the family," the park's operators said in a statement.