The 21-year-old has been named skipper for the side which also included fellow first-grade regulars Blake Green, Ken Maumalo, Agnatius Paasi and Leeson Ah Mau.
Papali'i made his debut for the club as an 18-year-old in 2018, clocking up 48 NRL games since, while also being capped by Toa Samoa and the Kiwis.
The squad also features a host of exciting talent including under-20 players Paul Turner, Rocco Berry, Edward Kosi and hooker Temple Kalepo.
Other familiar names selected for the pre-season tournament are Chanel Harris-Tavita, Adam Keighran, Sam Lisone and Leivaha Pulu.
The Warriors campaign begins against Newcastle on Friday night.
Meanwhile, North Queensland have unveiled Jason Taumalolo as skipper, but have resisted the temptation to unleash prized recruit Valentine Holmes.
Star back-rower Taumalolo will lead a squad that will feature five players making their debut for the NRL club - Kiwi international Esan Marsters, Connelly Lemuelu, Hamiso Tabuai-Fidow, Michael Bell and Reece Robson.
But fans will have to wait to see Holmes in Cowboys colours for the first time after the former Cronulla flyer's name was missing from their Nines list.
North Queensland will still have plenty of firepower with Marsters, Kyle Feldt, Josh McGuire, Coen Hess, Jake Clifford, Jake Granville and Scott Drinkwater included in a strong squad.
Gold Coast have also confirmed their Nines squad, including the likes of Jai Arrow, Ash Taylor, AJ Brimson, Tyrone Peachey, Bryce Cartwright and Anthony Don.
New Titans coach Justin Holbrook said the Nines was a chance for players to push for selection for next month's NRL season opener.
"There's always an element of interest in the Nines. Who(ever) does well definitely stakes a good claim for round one," he said.
"They'll always be young players at every club that really stand out, make the coaches go 'well jeez he's really in contention'.
"If he was already in contention he could force his way into the side."
The Warriors were drawn in a pool with the Knights, Sydney Roosters and Penrith Panthers.
Warriors NRL Nines squad: Leeson Ah Mau, Rocco Berry, Jackson Frei, Blake Green, Chanel Harris-Tavita, Temple Kalepo, Adam Keighran, Edward Kosi, Sam Lisone, Ken Maumalo, Taane Milne, Agnatius Paasi, Isaiah Papali'i (captain), Hayze Perham, Leivaha Pulu, Selesitino Ravutaumada, Jamayne Taunoa-Brown, Paul Turner