Set in the summer of 1985, the new episodes will see the gang once again fighting a mystery evil from another dimension with the help of police chief David Harbour and Winona Ryder.
Millie Bobby Brown will reprise the role of Eleven, while Finn Wolfhard as Mike Wheeler, Gaten Matarazzo as Dustin and Noah Schnapp as Will Byers will return as the trio of best friends.
New additions to the cast include British actor Cary Elwes, who portrays the town's mayor, Jake Busey as a local reporter and Maya Hawke as a shopping mall employee.
Trailers have hinted that the action will centre around a travelling fairground as well as the Upside Down, the alternate dimension where much of Stranger Things is set.
Stranger Things season three is available on Netflix now.