Tudor, who played for North Melbourne and Geelong in the AFL before turning his hand to coaching, will pack up his desk at Skilled Stadium this week and shift to Moorabbin where the Saints are beginning their 2009 campaign.
As a player, Tudor appeared in 60 matches for the Cats, including the 1994 and 1995 AFL grand finals.
He started coaching in the TAC Cup, where he was involved in premierships as an assistant coach with the Calder Cannons before taking over the main job at the Western Jets.
He coached the Cats' VFL team for the past four years – including guiding Geelong's seconds to the 2007 premiership.
Tudor's appointment at the Saints is another step up as he continues his coaching career.
"I'm excited to seize this opportunity to work with a young and dynamic club that has the potential to achieve great things," he said.
"I hope to draw upon my past experience to contribute to the Saints and very much look forward to embracing the challenge ahead."
His appointment also comes at St Kilda comes at the right time for the Saints, who lost former assistants John Barker and Anthony Rock back to their former clubs at the end of the 2008 season.
"After a long and thorough interview process, the St Kilda Football Club is extremely happy to announce that Leigh Tudor has joined our coaching panel," Saints football manager Greg Hutchison said.
"We had many high calibre applications for the position and know that Leigh's services were highly sought after.
"His coaching experience at Geelong is important as they have clearly been the benchmark team of the AFL throughout the last couple of years and Leigh has been a fundamental part of their success. We welcome Leigh to the club and look forward to working with him to achieve on-field success."
