The reformed electronica duo join Basement Jaxx, Dizzee Rascal, Biffy Clyro and The Prodigy on the Scottish event's lineup.
Rock Ness is held on the banks of Loch Ness on June 12, 13 and 14. Tickets are on sale now.
"Orbital are legends and they are a great addition to the Rock Ness Saturday night lineup," said festival director Jim King. "Listening to tracks like 'Chime' and 'Belfast' in such a dramatic setting is going to be a highlight of the weekend."
Orbital's live coomeback marks the 20th anniversary of their debut release 'Chime'.