The 58-year-old Australian guided the English outfit to a fifth-place finish in 2023 – their best season in 15 years.
But he said the opportunity to return to his home state was too good to turn down.
"It was an attractive option," said Kiss, who spent eight years with the Irish national side as assistant coach, helping them to three Six Nations titles (2009, 2014, 2015) and a Grand Slam (2009).
"The opportunity to return home to Queensland and coach at a successful club in a new world-class facility at Ballymore was something which appealed to me greatly."
"The Reds have an exciting roster which I am really looking forward to working with," he added in a statement late Thursday.
Kiss replaces former All Blacks forward Thorn, who stepped down at the end of last season.
Thorn had been in charge since 2018, coaching the Reds to a Super Rugby AU title in 2021.
Meanwhile, the Melbourne Rebels have signed English scrumhalf Jack Maunder on a one-year contract.
The 26-year-old, who has made 149 appearances for Exeter, said he had long been a fan of Super Rugby.
"When the opportunity came up to come and play in a different country and play in a competition I watched since I was a kid, I was extremely grateful," he said.
Maunder, capped once by England in 2017, added that he "couldn't be more excited to learn and develop as much as I can for the Rebels".
