The 24-year-old was a certainty to be included in coach Steve McNamara's 24-man squad before dislocating his shoulder during the Broncos' 16-11 win over Canterbury Bulldogs in the last round of NRL matches at the weekend.
Keighley-born Reed, who made his England debut in the 2011 Four Nations Series, was recently sidelined with a collarbone injury and has now been told he needs shoulder surgery.
McNamara received the news during a World Cup promotional visit to the Christchurch C of E School in Warrington, where organisers unveiled a sponsorship deal with Warrington-based online fashion retailer Get The Label.
"It's bad but I've just got off the phone so I can't tell you the full extent of the injury," McNamara said.
"He won't be available for selection, which is very disappointing for Jack.
"Jack's really upset about it. He's been desperate to be available for the World Cup.
"His collarbone would have been fine with another couple of weeks of recovery and rehab but I saw him do it (via satellite television).
"We didn't think it was going to be that bad but I've had confirmation from himself and his surgeon that he needs to have it operated on immediately so it's a significant injury."
Reed would have been expected to line up at centre alongside Leeds three-quarter Kallum Watkins and his injury could pave the way for Huddersfield's Leroy Cudjoe or Leeds' Zak Hardaker.
McNamara added: "It's very disappointing for us but this is why we put programmes in place so that, if something like this does happen, we have other candidates to jump in and fill that spot.
"Obviously Leroy and Kallum Watkins have been played the majority of the time for us in the last year and Zak filled in for us this year and we've got quite a few other strong candidates as well.
"It's not terminal for us as a team. I would have been very surprised had we got through to the selection date with everyone available."
McNamara will finalise his squad before the October 5 Grand Final and put them through their paces at a training camp in South Africa before a warm-up game against Italy on October 19, a week before the opening World Cup match against Australia.
- Sports & Recreation
- Steve McNamara
- Canterbury Bulldogs