Tuivasa-Sheck is on a million-dollar contract with the Warriors, but has regularly been linked with a move to rugby union in a bid to play for the All Blacks at the 2023 World Cup.
The star fullback, along with Warriors coach Nathan Brown and chief executive Cameron George, fronted a press conference early this afternoon to announce his decision.
Tuivasa-Sheck, who joined the Warriors in 2016, said he was keen to make the most of his last season with the club.
"The club have been supportive of the request, and I'm so grateful.
"Again, 2021 is my focus with this club and with these players. I'm excited about this year, and so should the Warriors and the NRL fans."
Tuivasa-Sheck said rugby was a game he grew up playing, and it had always been there in the background. But he said he wouldn't be looking into the detail about where he'd be playing, or even what position, until the end of the NRL season.
"I'll be talking rugby in November, at this stage I'm all league."
The 27-year-old skipper said he wouldn't be making any assumptions about what he might achieve in rugby union.
"I've been getting a lot of people saying 'you'll be going to the All Blacks', but that's a bit disrespectful. My whole thing is just to go back and play rugby.
"You don't just walk into a brand like the All Blacks, you've got to earn your way in."
George said the decision to release Tuivasa-Sheck from the final year of his contract would allow the 2018 Dally M medal winner to "chase his dream" in New Zealand rugby.
"This isn't a bombshell for the club - we've been discussing this for a number of weeks now.
"We wish Roger all the best in 2022 and beyond. However the important thing for us, our fans, our members and our commercial partners - and particularly Roger - is that 2021 is our focus.
"All the players are full supportive of this decision, and it's really galvanised the squad here.
"As a club, we're comfortable with it. Roger deserves this opportunity, we've worked with him and his management to get to this point, and we're looking forward to the future."
The Warriors squad is currently in Tamworth before relocating to the Central Coast next week.
The NRL seasons starts on March 11, with the Warriors' first game against the Titans two days later.