The 20-year-old center has agreed to a six-year contract extension with the Islanders, although the paperwork has yet to be completed, a source told ESPNNewYork.com.
Tavares will receive $4 million in the first year, $5 million in the second, then $6 million each of remaining four years for a $33 million total deal and an average annual value of $5.5 million, a source told ESPN.com's Pierre LeBrun.
The Islanders sent out a release Wednesday afternoon announcing a 1 p.m. ET Thursday news conference regarding Tavares' "future."
Newsday first reported the negotiation talks late Tuesday night.
Islanders general manager Garth Snow declined to comment on the discussions, but said his intent is on keeping Tavares for years to come.
"We want John to be a part of this organization for a long time," Snow said when reached by phone Wednesday morning. "I don't think there has been any deviation from that plan for either party in that regard."
Tavares, who turns 21 next week, was headed into the last year of his entry-level deal.
The Mississauga, Ontario native, selected first overall by the Islanders in 2009, finished with 29 goals and 38 assists last season.
Tavares told ESPN.com's Pierre LeBrun last week that he had no plans to leave Long Island.
"I'm committed to Long Island and the Islanders. They've been great to me," he said during an NHL media tour. "We have a great bunch of guys and I'd love to be part of turning this around from where it was and bringing us back to credibility, respectability and being a team that's constantly in the playoffs and competing for the Stanley Cup."
Snow said he wasn't surprised to hear such comments from the young center.
"That just reaffirms the fact he loves being part of the organization," Snow said. "We love having him here, wearing our jersey."
Katie Strang covers the NHL for ESPNNewYork.com.