He told Collider: "It's pretty much set to go, this fall. I think now Chloë and Chris (Mintz-Plasse) are on board. I'm certainly set up to do it. Jeff Wadlow is to direct. Yeah, I think it's going to happen."
Johnson also revealed that he has read the script for the sequel, saying that it is likely to get an R certificate, keeping the "standard... from the first film".
The 22-year-old actor will next be seen in Oliver Stone's drug thriller Savages, alongside Salma Hayek, Benicio Del Toro, Blake Lively and Taylor Kitsch.