As a player, Walters won six NRL Premierships, made 20 State of Origin appearances, and 11 Test matches for the Kangaroos, including being part of Australia’s 1992 World Cup-winning team.
Chairman Eamonn McManus added: “Kevin’s vast experience at both club and representative levels is self-evident.
“His motivation to succeed with the task at hand was both clear and compelling to us, as shown by the major career sacrifices that he is making in Australia to join St Helens.
“This is a major statement of ambition both by St Helens and by Super League.”
Eamon O’Carroll will continue as Saints interim head coach until the end of this season following the departure of Paul Rowley in July after less than a year at the helm.
Saints have endured a torrid season with injuries heavily contributing to them being in danger of missing the Super League play-offs for the first time ever, sitting seventh in the table with three games remaining.
Former boss Paul Wellens opted not to extend his contract last year following a season when Saints pulled off one of the greatest comebacks ever when they beat Leeds Rhinos in the Super League play-offs.
On O’Carroll, McManus added: “He has been magnificent for us under testing circumstances, and I am sure that our fans will remain firmly behind him and the team.”
