Enright will swap Kardinia Park for Moorabbin ahead of the 2022 season after five seasons as an assistant with the Cats.
The triple premiership defender will bring an unparalleled wealth of experience to the Saints as they embark on a hopeful return to finals football next year.
Across his 332 games with Geelong, Enright amassed the honours of six All-Australian selections and two best and fairest gongs to add to his three premiership medallions.
The Kimba product stated his excitement to be joining St Kilda during an exciting period for the football club.
“I’m really looking forward to this next chapter with the St Kilda Football Club,” Enright said.
“I’m proud of what I learned throughout my time at the Cats, and am thankful for all the opportunities they’ve given me, however I’m looking forward to a new challenge.
“I believe the Saints have a really exciting young group and I can’t wait to get to work.”
Enright's arrival is the Saints' latest change to their coaching and football operations staff structure.
Assistant Coaches Aaron Hamill and Adam Skrobalak, Head of High Performance Matt Hornsby and Senior Physio Andrew Wallis all departed the club last month.
St Kilda managed a 10th placed finish this season after recording 10 wins from their 22 matches in 2021.