Seacrest and Ora are set to anchor the celebrations live from Times Square in New York City.
Chance the Rapper will host from Chicago, while former NFL star Rob Gronkowski and Julianne Hough will broadcast from Las Vegas, with further details for a Puerto Rico segment yet to be revealed.
The event will be broadcast live on ABC from 8 p.m. EST on 31 December, with streaming available on Hulu the following day.
Ryan Seacrest has been involved with ABC’s New Year’s Eve special since 2005, having inherited the main hosting role from Dick Clark.