Rabbitohs coach Anthony Seibold.

Brisbane have announced Anthony Seibold will join the Brisbane Broncos as coach effective immediately on the same afternoon they terminated the contract of Wayne Bennett.

Seibold had already agreed to join the club as coach from 2020 onwards, but he will now be Brisbane's coach for 2019 as well after the departure of Bennett.

Seibold has been granted an immediate release by South Sydney, and will be at the Broncos on Monday for the first day of pre-season training with the full squad in attendance.

Meanwhile the Rabbitohs have confirmed Bennett as their new coach on a three-year deal.

"I'm really pleased it's all resolved and that I can join this great club with a free mind, knowing I did the right thing by the fans, staff and players," Bennett said.

"I'm really looking forward to being at South Sydney and working with the players, staff, Board and all of the members.

"It's a wonderful club, South Sydney, and I feel privileged to have the chance to coach this team."

Broncos CEO Paul White said the change was necessary for the club's 2019 prospects.

"We no longer had faith that we could give ourselves the best chance of performing if we continued on the path we were continuing on," White said on Sunday.

"We considered the preparation and bringing a new coach in and what that would mean but the two decisions were made independently of each other - who comes after Wayne, that's separate to our decision today to end Wayne's services for 2019.

"I think the reaction from the players will be very positive and I don't say that out of any disrespect to Wayne. I think players require certainty and while today's announcement is unfortunate we have the ability to move forward."

The Rabbitohs released Seibold from the final year of his two-season deal, paving the way for him to begin his reign at the Broncos and for Bennett to arrive at Redfern 12 months ahead of schedule.

The issue came to a head when Seibold told NewsCorp the saga surrounding the two coaches was having an impact on his family.