The 20-year-old has played for the Junior Kangaroos, NSW Under 20s and in 2017, was named at centre in the Holden Cup Team of the Year.
Ramien, who plays for the Cronulla Sharks, made his NRL debut in Round 26 of last season, in a match against the Knights.
“Jesse is a great young talent and he will be able to continue his development at the Knights,” GM Football Darren Mooney said.
“Jesse is an imposing centre, with size and speed and will be a great addition to our outside backs when he joins us next season.
“Our squad is a great mix of youth and experience; a player like Jesse will not only add further depth, but he will join us a long-term centre option.”
Ramien attended Hunter Sports High and played junior league locally with the Valentine Devils.
“He has played junior football with a number of our young players and looks forward to linking back up with them here at the Knights,” Mooney added.