The 32-year-old, who briefly appeared for the Pilgrims in 2018, has arrived on loan from National League side Bromley, having enjoyed prolific spells with King's Lynn Town and Barnet since his departure from York Street.
Marriott played under Ian Culverhouse and Paul Bastock at the Walks Stadium – and earned back-to-back promotions to National League North and subsequently the National League under their management.
He will wear squad number 22 during his spell with the Pilgrims, which is subject to final Football Association ratification.