The 24-year-old made his debut for the Black and Whites in 2013 and has gone on to become a vital part of coach Lee Radford's team, earning a place in the 'Super League Dream Team' this year.
Shaul, who has scored 45 tries in 74 Super League appearances for Hull FC, has now inked an extension that will keep him at the KCOM Stadium until the end of the 2020 season.
The target now for the Hull-born player is to improve on a stellar 2016 campaign after helping the club claim the Challenge Cup while a spot in the England team is also on his radar.
"I'm buzzing to sign for a further two years with the club," he said. "I've supported Hull all my life so when I had the chance to sign a new contract I jumped at it.
"I like to think I went well last year but I know I've got improvements in my game that I need to make if I'm to make the England squad, which is my ultimate aim."