Lethlean will become the Saints' general manager of football following a restructure sparked by former chief operating officer Ameet Bains' move to Western Bulldogs as their new chief executive officer.

Lethlean resigned from his AFL position in July after details of a relationship with a younger staffer were made public. He was overlooked for CEO roles at Collingwood, Carlton and Hawthorn.

Finnis said Lethlean's conduct was taken into account by the board before they "unanimously" approved of his hiring.

"Of course it was [considered]," Finnis said. "The reality of the situation and the opportunity was that we would not have been in a position to secure Simon if it hadn't have been for the circumstances he left the AFL six months ago.

"You have got to embrace that, examine that and then ultimately be satisfied that Simon is completely taking ownership of the poor decisions that he made and taking accountability and ultimately in a position where he is ready to move on.

"The fact he has invested, as a priority, the time into winning back the trust of those who are most important to him - and those people aren't in football - that also gives us confidence he is ready to come back in and recognise that he needs to win back the confidence of people in football who want to judge him for his performance."

St Kilda and Finnis have worked hard over the past 10 years to change the club's culture and public perception.

He said Lethlean's hiring did not fly against the club's values.

"One of the things about being inclusive and fostering a sense of belonging is that you recognise that people deserve a second chance," Finnis said. "For us, we are really willing to give Simon an opportunity to have a second crack at his career in the AFL industry because we believe that he wants to make every post a winner and that aligns really closely with what we are trying to do."

Lethlean said via a club statement that he was thrilled to join the Saints.

"St Kilda is a club with a clear vision, a united administration, a very strong coach and a young talented list," Lethlean said.

"I am extremely pleased to be joining the club in this new role, and feel humbled to be given a second chance in the industry that I love.

"I am passionate about football and am thankful to Matt Finnis, Alan Richardson, Peter Summers and the entire board and club for giving me this opportunity.

"I spoke to the playing group and the entire staff this morning, and outlined my passion for football and the opportunities I see in the role.

"I believe I can be part of a team that delivers real and sustained success to St Kilda Football Club."

The former AFL No. 2 will start with the Saints on January 8 when staff and players return from their Christmas break. He was hired after accounting firm Ernst & Young conducted a review of the club's football department.

Prior to being the AFL's head of football, a role he held for six months, Lethlean had worked in legal, broadcasting and scheduling roles with the league since 2004. Prior to that he worked as a solicitor.

Finnis said Lethlean's experience across football and every aspect of its administration made him the stand-out candidate for the role.

Fairfax Media reported earlier this month that AFL boss Gillon McLachlan had made representations to AFL clubs suggesting they should hire Lethlean, his close friend and long-time colleague.

McLachlan is understood to have said Lethlean sought a CEO position and not a head of football department role.