Billy Slater has taken up a leadership role with AFL club St Kilda less than a fortnight after ending his illustrious rugby league career.

The legendary full-back retired after Melbourne Storm's NRL Grand Final defeat to Sydney Roosters at the end of last month.

Australia, Queensland Maroons and Storm great Slater has agreed to take on a part-time position working with Saints players, coaches and high-performance staff.

Slater will serve as a mentor, passing on his experience in relation to professionalism, training standards and matchday performance across the whole playing group.

"Billy's sporting resume is second to none, and he will add great value to our club," Saints general manager of football Simon Lethlean said.

"He's been an impressive leader in his own right, but he's also been a key member of a culture that is highly respected across all sports.

"Over the course of the season, we identified that there was an opportunity to strengthen our leadership and development programs, and we think Billy can play an important role in that.

"He will work closely with our current leaders as well as our emerging leaders to help them develop their leadership capacity and optimise their professionalism and performance."

Slater is set to start work early in pre-season.