Thorn on Tuesday put to bed speculation he would quit his post, confirming he will complete his contract by seeing out the Super Rugby Pacific season.
"The past six seasons have been equally enjoyable as they've been challenging, but I'm fortunate for the opportunity and hope I when I do leave here, the program and culture is in better shape to when I started the job in 2018," Thorn said in a statement.
"The job's not finished. We've got six games left and then finals – and we've got a plan to get there."
Thorn won NRL titles with Brisbane and played for both Queensland and Australian in rugby league, while also winning a Rugby World Cup with New Zealand and Super Rugby silverware with the Crusaders.
He was still playing second-tier professional rugby in his early 40s and is in his 30th consecutive season as either a player or a coach.
The dual-code sensation has coached the Reds since 2018, overhauling the program with bold decisions to let Quade Cooper, Karmichael Hunt and James Slipper go as he blooded a new wave of local talent.
A Super Rugby AU title in 2021 was the high point, but the Reds have struggled against New Zealand opposition and this year slipped to 3-5 after costly losses to Melbourne and the Brumbies.
Thorn admitted after the loss to the Brumbies, their first against an Australian rival at Suncorp Stadium in 15 games, that he had "possibly" taken the side as far as he could.
A win in Samoa on Friday against Moana Pasifika improved the Reds to sixth place in a 12-team competition where the top eight contest finals.
The club are optimistic they can still make a dent in the post-season and have resisted the urge to make an early change.
"Upon his appointment as head coach in 2018 he had to make some tough decisions – unpopular decisions, but they were for the betterment of the whole organisation," Reds chief executive David Hanham said.
"Built on care, humility and hard work, he changed the culture at Ballymore.
"Brad will continue and ... his fellow coaching staff and playing group are all equally committed with the goal of playing finals for a fourth-straight year."
Hanham said the club was yet to begin a process to decide on the next head coach.
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