In his place, Des Hasler has been appointed as the new head coach of the Titans for the 2024 season and beyond, although the club have given no clarity on the length of his contract.
The Titans have also not confirmed whether Hasler will take over immediately, or whether an interim coach will be appointed, however, News Corp are reporting that it's a three-year deal for Hasler, while Jim Lenihan - who is a QLD Cup winning coach - will be appointed as the interim boss.
The Titans have failed to realise their potential under the coaching of Holbrook.
In what is his third season with the club, the Titans finished ninth in 2020, snuck into the finals with an eighth-placed finish in 2021, and wound up 13th at the end of 2022.
It didn't work for the Titans, and, despite the arrival of Kieran Foran and Sam Verrills, it has been a difficult start to 2023 for the Titans, who have lost three of their last four and hold a six and seven record.
The club confirmed Holbrook had parted ways with the club by agreement, with CEO Steve Mitchell thanking Holbrook for his contribution.
“We are grateful to Justin for his contribution to the club over the past four seasons,” said Titans CEO Steve Mitchell in a statement.
“We are here to bring success to the Gold Coast and in order to do so we feel that this is the change necessary to deliver on our promise which is to win premierships.”
Holbrook's departure was heavily rumoured in the midst of the 2022 season, although he ultimately survived.
Hasler joins the club as one of the most experienced coaches in the game, with the former Manly boss sacked at the end of the 2022 campaign by the Northern Beaches club.
Hasler said he was looking forward to joining the Titans.
“I'm looking forward to joining the Titans and to the 2024 season,” Hasler said.
“The club has a strong playing roster, the region is blessed with emerging talent and the organisation is firmly embedded in the community.
“I'm confident we can deliver success to the region in the coming seasons.”