Fiore moves to the Holden squad after six seasons in a co-driver role at Kelly Racing, partnering Michael Caruso for five years before teaming up with Garry Jacobson for 2019.
Fiore and Pye have worked together before; the pair were LD Motorsport teammates back in 2013, Fiore's last season as a Supercars full-timer.
“I am thrilled to be joining Team 18," said Fiore.
"After a tour of the workshop and meeting most of the crew, it’s clear to me that [owner] Charlie [Schwerkolt] has put everything in place for Team 18 to succeed.
"I'm really looking forward to pairing up with Scott too. We were teammates in 2013 and I admire what he’s been able to achieve since then.
"I also really want to thank Mark [Winterbottom] for initially reaching out and starting the dialogue with Steve and Charlie."
Schwerkolt added that Fiore's experience made him the ideal candidate for the seat.
"Dean has had a really solid performance in his previous endurance campaigns, so it's really exciting to have him join the team alongside Scotty," he said.
"They are ex-teammates so I think that they will really work well together in the Enduro Cup for the first season with our new second entry."
The major backer of the team's second car is yet to be announced.