Dick Van Dyke says he will appear in “Mary Poppins Returns,” a sequel to the 1964 film in which he co-starred with Julie Andrews, as part of a high-powered cast that includes Emily Blunt and Lin-Manuel Miranda.

The new musical, directed by Rob Marshall, is scheduled to be released on Christmas Day 2018. Ms. Blunt will play Mary Poppins, a role Ms. Andrews portrayed in the first film.

“This one supposedly takes place 20 years later, and the kids are all grown up,” Mr. Van Dyke told The Hollywood Reporter. “It’s a great cast: Meryl Streep, Angela Lansbury and that guy from ‘Hamilton,’ ” a reference to Mr. Miranda, who will play a lamplighter named Jack, according to media reports.

Mr. Van Dyke, 91, will not revisit his character, Bert, the chimney sweep with a cockneyish accent who joined Ms. Poppins, a magical nanny who flew under the power of her umbrella, and her two young charges on a romp through Edwardian London.