Beveridge will remain with the Hawks for the rest of this season before joining Alan Richardson's team at Seaford in the newly created role.
After recent meetings to discuss whether the club needed a director of coaching, the Saints have opted for the 43-year-old, who is in his third year as an assistant with the Hawks.
The position is similar to that held by Richardson when he was director of coaching and strategy at Port Adelaide alongside coach Ken Hinkley in 2013.
There is a code of conduct clubs follow when targeting opposition coaches in season, and Hawthorn would have needed to approve talks between Beveridge and the Saints under those guidelines.
The Hawks would have been more open to the approach given Beveridge was moving to a different and more senior role at the Saints.
The AFL Coaches Association, which is currently being led by interim CEO Mark Brayshaw, said it did not wish to comment on the unusually early approach from St Kilda.
Beveridge played 118 games with Melbourne, Footscray and St Kilda between 1989 and 1999.
He has overseen the Hawks' backline, and football manager Chris Fagan said the club was disappointed to lose a coach of his credentials.
"Despite having offered Luke a contract to remain at the club beyond 2014, we understand his aspirations to step into a more senior role and this position at St Kilda allows him to do so," Fagan said.
"Luke’s been a fantastic contributor to our coaching team over the past three years, he’s developed great relationships with the playing group and has established a backline that’s well respected across the League."
Beveridge, whose father John has worked in the Saints' recruiting and development team for more than 30 years, said he was exciting about joining the club at the end of this season.
St Kilda football manager Chris Pelchen said the successful assistant's experience at "prominent AFL clubs" – he was development manager at Collingwood in 2009 and 2010 – made him an ideal candidate.
"The ongoing development of the coaching structure is a key focus of the St Kilda football department and the role of director of coaching is an integral part of this program," Pelchen said.
Fagan said Beveridge would see out his role with the Hawks' backline until the end of the 2014 campaign.
