A couple walking their dog made the discovery just after 8:30 a.m.
"We received a call from a citizen just saying that she had seen something she thought looked suspicious with this body lying face down," said Newport Beach police spokeswoman Jennifer Manzella.
As police documented the scene where the body was found, detectives gathered evidence on top of the bridge along Pacific Coast Highway.
Investigators have not yet determined a cause of death or identified the woman.
This is a busy area for boaters, kayakers and paddle boarders. The sight was disturbing for those on the water during the Labor Day holiday.
"That's not good. I come by here all the time, and I mean it's kind of an unsettling thing that that's what happened," said Orange resident Austin Carroll.
Anyone with information about this case was asked to contact Detective Ryan Peters at (949) 644-3779 or the Newport Beach Police Department's hotline at (800) 550-NBPD.