Cameron addressed CinemaCon via video from New Zealand, where finishing touches are being put in place on the film.
He promised giant technological leaps forward from the original, whose main characters Jake Sully (Sam Worthington) and Neytiri (Zoe Saldana) now have a family.
"We set out once again to push the limits of what cinema can do," said Cameron.
To reacquaint audiences with Pandora nearly 13 years after the smash hit original, which sparked a 3D wave in Hollywood, the first "Avatar" will be re-released in theaters in September.
'The next decade'
Movie theatre bosses are gathering at Caesars Palace in Las Vegas for their annual meeting, where Hollywood studios bring fresh footage and A-list stars to court the industry.
Marvel Studios boss Kevin Feige kicked off the morning's Disney presentation, telling attendees that planning for "the next decade" of the record-grossing superhero films was well underway.
Attendees also got an extended look at "Doctor Strange in the Multiverse of Madness," which is out next week.
Footage showed Benedict Cumberbatch's sorcerer battling an extra-terrestrial floating octopus, encountering a universe-hopping teenage girl, and attending his ex's wedding.
It will be followed by two more Marvel films this year -- sequels to "Thor" and "Black Panther."
Pixar showed 30 minutes of "Lightyear," an origin story for the beloved astronaut from "Toy Story," voiced by Chris Evans.
The movie, out in June, finds Buzz racked with guilt after marooning his crew of space rangers on a hostile alien planet.
In his bid to save them, he is forced to travel into the future -- aided by a cute robotic cat.
Also on show was "Amsterdam," an "original romantic crime epic" starring Christian Bale, Robert De Niro, Margot Robbie and Chris Rock among an A-list ensemble.
The 1930s period piece about three friends who "find themselves at the center of one of the most shocking secret plots in American history," which purports to be based on true events, comes out in November.
Universal then took the stage at Caesars Palace to show footage from the upcoming "Jurassic World: Dominion," out in June.
The film will team the franchise's recent stars Chris Pratt and Bryce Dallas Howard with those from Steven Spielberg's original almost 30 years ago, including Jeff Goldblum.
Goldblum joked that his character's famous line that scientists "didn't stop to think if they should" bring back the dinosaurs had been "aggressively ignored throughout the course of the next several movies."
Billy Eichner presented "Bros," the "first gay rom com ever made by a major studio," joking that it "only took a century."
"It's about something that we can all relate to -- how hard it is to simply find another tolerable human being to go through life with," said Eichner.
And Carey Mulligan discussed "She Said," based on the true story of journalists investigating Hollywood sex assault scandals who prompted the downfall of Harvey Weinstein, out November.
CinemaCon concludes Thursday.