The 36-year-old has been drafted in by the Monster Yamaha Tech 3 squad because Edwards is unable to participate in Valencia while he recovers from injuries sustained during the Malaysian Grand Prix at Sepang on October 23.
Edwards was due to make his final appearance for the Monster Yamaha Tech 3 squad at the Ricardo Tormo Circuit after a long and successful career with Yamaha in the MotoGP World Championship, which started back in 2005.
The Texan though will undergo an operation to repair cartilage damage around the top of the hume rus bone in his left arm after he was involved in an incident with Marco Simoncelli and Valentino Rossi on the second lap of the Sepang race.
Tragically, Simoncelli succumbed to injuries sustained in the accident.
Hayes, who won his second successive American Superbike crown for the Monster Energy Graves Yamaha Team in a dramatic final round in New Jersey, was due to test the Monster Yamaha Tech 3 YZR-M1 machine the day after Sunday's final race.
Yamaha US and Monster Energy arranged the test appearance to reward Hayes for capturing the American Superbike title for the second year in succession in 2011.
Hayes will now join British rider Cal Crutchlow when practice for the Valencia round gets underway on Friday morning.