McCullough will join the top 30 squad immediately after being targeted by the Knights to improve the club's hooking depth following the loss of first string No.9 Jayden Brailey for the rest of the season following a knee reconstruction.

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The 30-year-old will bring 260 NRL games of experience with him to the Knights.

"We are in a position thanks to good governance from Alex McKinnon to have a top 30 spot available to secure someone of Andrew McCullough's calibre," Knights coach Adam O'Brien told Knights media.

"As one of the leaders of the club, it's my responsibility to be looking at recruitment and retention to have us field a competitive team each week.

"We are on foreign ground with the draw stating we have to play 18 games straight and we need to forward plan.

"We have faith in the depth of our roster but also recognise that promising talent Chris Randall is on the start of his journey having joined the team as a train and trial player late last year.

"Connor Watson is another exceptional player who can fill the role at Nine but given his versatility it's important for the make-up of the team to keep him in his current explosive role.

Taking a holistic approach to the team, the recruitment of Andrew McCullough gives us valuable experience at the highest level."