The agreement with the unannounced NRL club was settled undisclosed transfer fee as compensation due to his departure. While the Saints didn't confirm what NRL club they came to an agreement it is likely the Parramatta Eels, who have been heavily linked to the hooker.
Over the course of the past two seasons, Lussick appeared in 52 games for the Saints, having joined them from the Parramatta Eels- in which he played nine games.
His arrival back to the Eels comes as recruit Josh Hodgson was ruled out for the season with a neck injury and they didn't want youngster Brendan Hands to play the entire 80 minutes as they look to clinch a spot in the NRL finals.
"As revealed by Head Coach Paul Wellens following the Saints' Challenge Cup Semi-Final defeat to Leigh Leopards, the hooker has played his final game for St. Helens, and he leaves with the best wishes of everyone at the Club," the St Helens statement read.
"The Saints have been working on a suitable replacement for Lussick to join the squad immediately, and details on this player will be confirmed in due course.
"In his time at the Totally Wicked Stadium, Lussick helped the Red V secure the League Leaders' Shield and the Super League title at Old Trafford in his first season, and earlier this year was part of the team that made history by beating Penrith Panthers to win the World Club Challenge.
"Lussick leaves the Club having made 52 match appearances, scoring 11 tries and kicking 7 goals.
"The Saints would like to thank Joey for his efforts as a St. Helens player, and we wish him the very best for the future."