The 29-year-old forward has signed what the Red Devils describe as a "long-term contract" at the AJ Bell Stadium.
McCarthy has previously played in Super League with Hull KR and Warrington, helping Wolves win the Challenge Cup.
"Tyrone is a really big signing for us. He is a bloke that leads with his actions," said head coach Ian Watson.
"Not only will he bring ability and experience to the side, but also leadership.
"His attitude and commitment to play for his team-mates is first class and that is exactly what we need at this stage of the season."
McCarthy, who has 12 international caps and played for his country at the 2013 World Cup, will be available for the Super 8s phase of the season, with Salford sitting third in Super League with one round of the regular season remaining.
Salford have signed Ireland international Tyrone McCarthy from Australian NRL side St George Illawarra Dragons with immediate effect.