Tedesco, the 24-year-old who was the Dally M Fullback of the Year in 2016, will join the Roosters from next year.
A New South Wales State of Origin representative in 2016, Tedesco has played 78 NRL matches.
"James is a tremendously exciting talent whose signature we are pleased to have secured and we look forward to welcoming him to the Roosters in 2018," Roosters chief executive Joe Kelly said.
— Sydney Roosters (@sydneyroosters) May 4, 2017
Tigers CEO Justin Pascoe said his club were disappointed Tedesco had decided to leave.
"I'm sure this decision hasn't been made lightly by James and while it will be disappointing to see him leave at season's end we will continue to provide him with all the support he needs," he said.
"James is a quality young man, both on and off the field, and I'm sure he'll be a great addition to his new club."