The homegrown Academy product, 21, has had to bide his time for chances behind the experienced Scott Grix but is seen as the club’s long-term No1.
Wakefield-born Jowitt made his debut at St Helens in 2014 and has scored nine tries in 46 games for Trinity so far.
After agreeing a contract until the end of 2021, he said: “I am really happy to have signed.
“Three years means that I can cement my place here at the club and hopefully secure that full-back spot over the next couple of years.”
Wakefield head coach Chris Chester added: “Max is a talented young player.
“He’s still only young and has so much more development and areas to grow as a player.
“He has stepped up over the past couple of months and there is a fantastic opportunity for him to secure his spot in the first-team.”