The 30-year-old New South Welshman, who is still contracted to the Sydney Roosters through to the end of 2027, inked a two-year deal for 2028-29 prior to Tuesday's announcement.
Despite his ongoing contract, the Roosters granted him permission to leave at the end of this season to head to Wollongong for a single season prior to his move to Port Moresby.
The versatility of Watson, who has often alternated between lock and hooker throughout his career but has also deputised as a five-eighth and even a fullback on occasion, was trumped by "his sense of purpose and the way he treats people", according to PNG Chiefs CEO Lorna McPherson.
“He leads with kindness, he listens, and he brings a calm strength into every environment he enters," McPherson stated.
"We wanted people who would genuinely feel at home in Papua New Guinea, and people Papua New Guinea would feel proud to welcome.
“Connor immediately connected with the country and our vision for what this club can become. We know he will have a significant impact both on and off the field as we build towards 2028."
Watson and his partner were spotted in Port Moresby a few weeks ago to discuss his signing, a time during which they "fell in love with the country" according to Chiefs General Manager Football Michael Chammas.
“Connor has made it clear from the outset that he wanted to be part of the PNG Chiefs and this incredible journey we are building," Chammas said.
“Connor is the type of player every club wants. He is selfless, tough, professional and incredibly respected across the game. His versatility and experience will be invaluable for us as we continue building our squad towards 2028.
“Every signing matters for a new club, but there is something exciting about seeing the roster continue to build piece by piece. Connor becoming Signing 003 is another important moment in the journey of the PNG Chiefs."
The five-time NSW Origin representative will bring 11 years and potentially more than 200 games of first grade experience to Port Moresby by the time of his arrival, appearing for the Roosters ten times in 2026 to take his career tally to 177 matches.
Watson joins NRL stars Alex Johnston and Jarome Luai on the three-man PNG roster.