The 25-year-old hooker should now stay at the club until the end of the 2016 season.
“I am happy to be back at Wakefield,” said Howarth.
“I was here in 2011 and when I found that there was an opportunity to come back to the club, I jumped at it.
“I was at Hull FC and only played 8 or 9 games, I was offered a lot more game time here and I want to play rugby. So it was the right decision for me to make.”
“I am delighted to welcome Stuart back to the club, and he had a successful stint here in 2011, and will bring some much needed defensive attribute to our squad.
Wakefield chairman Michael Carter added: “He can cover a variety positions for us and will be a valuable member for the remainder of this season and next season.”