D23: The Ultimate Disney Fan Event is the company's biennial exposition event, where it previews upcoming movies, shows, experiences and products, in addition to honoring its history. This year's event is taking place at the Anaheim Convention Center through Sunday.
The new E-ticket dark ride -- meaning it's an indoor attraction that uses the latest technology -- is part of an expansion of the Avengers Campus section at California Adventure.
Avengers Infinity Defense will see the return of Thanos, the Big Bad of Marvel's Infinity Saga. The version of the character in the ride -- King Thanos -- is from a reality where he triumphed over the heroes.
D23 LIVE UPDATES: Here's every major announcement from Disney's ultimate fan expo
The ride will see guests welcomed as recruits to Avengers Infinity Defense by Ms. Marvel, who will be played by Marvel Cinematic Universe actress Iman Vellani, before they reassemble the Avengers to battle King Thanos across multiple worlds, according to Disney.
Also reprising their MCU roles will be Jeremy Renner as Hawkeye, Anthony Mackie as Captain America and Chris Hemsworth as Thor, in addition to the previously announced Robert Downey Jr. as Iron Man.
The ride will mix massive physical sets with huge media scenes, the company noted, as guests travel to iconic locations like Asgard, Wakanda and New York City.
The 2028 expansion will double the size of Avengers Campus, Disney said, and add a second ride, Stark Flight Lab. That ride will include Brie Larson as Captain Marvel, Mackie as Captain America and Downey as Iron Man, acting as flight instructors.
At Hong Kong Disneyland, the Avengers Research Testing Labs will open at the Marvel area that's under construction and feature Spider-Man as one of its stars.
Spidey is getting his own dedicated land at Shanghai Disneyland. The final piece of the track for the area's roller coaster has been installed, Disney said on Saturday.
Disney is the parent company of Marvel and this station.