Paul McGregor will leave his post as St George Illawarra Dragons head coach after Friday's NRL clash with Parramatta Eels.
McGregor took the helm of the Dragons in 2014, but they have made the finals just twice since then.
The 52-year-old and the club agreed on Thursday that McGregor should leave the position, with assistant Dean Young to be interim head coach for the rest of 2020.
"I wish to thank the Dragons for allowing me to be head coach over the past seven seasons as well as everyone who has been involved in my journey at this proud club," McGregor said.
"I approached the club's chief executive Ryan Webb earlier in the week regarding a number of matters and we eventually came to an agreement that this week will be my last as coach of the Dragons.
"I understand a fresh face and new voice is needed to move the club forward. I hope this decision will provide clarity to the playing group, the entire staff and our passionate Red V members and partners regarding the direction the club is headed.
"After 25 years with the Illawarra Steelers and St George Illawarra as a player, staff member, captain and coach; I viewed my positions as a series of privileges not obligations.
"We haven't met performance expectations over the past 18 months, and I take acceptance of responsibility. I had the opportunity to build my team, which we did in 2017 and 2018. Unfortunately, we have not put that same side on the field since for a number of reasons.
"Dean Young and the team have a fantastic opportunity over the next six weeks to build into the 2021 campaign. Dean deserves this great opportunity to showcase his capabilities in the head coach role."
Ahead of facing the Eels, the Dragons are 12th in the NRL, six points adrift of eighth-placed Cronulla Sharks.
Dragons chief executive Ryan Webb thanked McGregor, who represented Australia during his playing career.
"The decision to part ways with Paul was one that nobody took lightly," Webb said.
"Paul has had a 25-year association with our club and the joint venture's founding club, the Illawarra Steelers and has shown great passion, integrity, character and a strong work ethic throughout this time. He will forever be a part of the Dragons family.
"It's important to note that Craig Young excused himself of any decision making pertinent to Paul's departure and Dean's appointment. As such, for as long as Dean remains coach, Craig will take a voluntary leave of absence from the board.
"The club will now turn its focus to establishing the crucial process of appointing a new head coach for the 2021 season and beyond."