Hawke and co-star Julie Delpy starred in 1995's Before Sunrise as two strangers who fall in love during an evening in Vienna.
In Before Sunset, the characters reunite nine years later when Hawke's character, now married, travels to Paris to promote a book he wrote about their brief love affair.
Reality Bites actress Delpy and director Richard Linklater shared writing credits on the second movie, earning an Oscar nomination for 'Best Screenplay'.
In 2004, the filmmaking trio said that they had plans to return to the characters after another nine years, and Hawke has now revealed that production on a follow-up is imminent.
He told Indiewire: "We're also doing a follow-up to Before Sunrise and Before Sunset, so that will be fun. We're going to shoot that this summer."
The 41-year-old actor was vague when asked about the plot of the upcoming movie.
"I've gotten into trouble, so I'm sworn to secrecy," he joked. "The biggest change between this one and the last one is the internet."
Since Before Sunset, Julie Delpy has written and directed her own romantic series, starting with 2 Days in Paris and its recent follow-up 2 Days in New York.
Watch the trailer for Before Sunrise below: