Howarth, 23, originally joined the Mariners on loan from Salford City in December 2019 and went on to score five goals in 13 appearances.
He enjoyed a brief stint at Guiseley before returning to the Marine Travel Arena on a permanent deal in May 2021.
The Burnley-born midfielder made 44 appearances in all competitions last season and has featured another 12 times since the 2022/23 campaign began.
Marine manager Neil Young said: “Mark is someone who we have had with us for a while now, initially on loan and then permanently for a number of seasons.
“He can play in a number of positions but I believe there is so much more to come from him.
“He is technically outstanding, and with a little more self-belief he will do really well for us.”
Photo credit: Marine
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