Ricciardo, 33, hinted strongly at a return to Red Bull in a reserve capacity after leaving McLaren without another full-time role set up.
"The smile says it all," he said. "I’m truly excited to be coming back home to Oracle Red Bull Racing as their Third Driver in 2023. I already have so many fond memories of my time here, but the welcome from Christian [Horner], Dr [Helmut] Marko and the entire team is something I’m sincerely appreciative of.
"For me personally, the ability to contribute to and be surrounded by the best team in F1 is hugely appealing, whilst also giving me some time to recharge and refocus. I can’t wait to be with the team and support with simulator work, testing sessions and commercial activities. Let’s go!”
Red Bull Team Principal Christian Horner added: “It is great to bring Daniel back into the Red Bull family. He has enormous talent and such a brilliant character; I know the whole factory is excited to be welcoming him home.
“In his role as test and third driver, Daniel will give us the chance to diversify, assisting in the development of the car, aiding the team with his experience and knowledge of what it takes to succeed in F1. We’re very pleased to be working with Daniel again and look forward to everything he will bring to the team in 2023.”