On September 23, 2024, it was officially announced that Freddie Prinze Jr. had signed on to reprise his role as Ray Bronson in the new sequel.
It was reported in 2014 that director Mike Flanagan and writer Jeff Howard were developing a reboot of I Know What You Did Last Summer (1997). In a 2016 episode of the "Shockwaves" podcast, Flanagan said the film would not having any connections to the 1973 novel nor the 1997 film, and the scope of the film necessitated an estimated budget of $15-20 million. This planned film eventually fell through, and instead a TV series reboot was released, I Know What You Did Last Summer (2021).
Jennifer Kaytin Robinson has stated that the movie would not ignore the events of I Still Know What You Did Last Summer (1998).
On Friday, December 13, 2024, it was officially announced by Jennifer Love Hewitt herself that she would be returning as Julie James in the new sequel.
Brandy Norwood, who played Karla in I Still Know What You Did Last Summer (1998), wanted to reprise her role in the sequel.