The 25-year-old striker, who scored a penalty in Hartlepool United's promotion final shootout victory over Torquay United in June, has put pen-to-paper to join the Pilgrims ahead of the 2021-2022 campaign.
Elliott had previously enjoyed successful spells in National League North with Chester FC and Alfreton Town (loan) – after previous stints playing abroad in America and Spain.
"Danny comes here on the back of a recent promotion with Hartlepool, so is full of confidence," reflected manager Craig Elliott.
"After meeting Danny, he had a real desire to continue to be successful, so I am delighted that he felt he could do that at Boston United.
"He has caught the eye on a number of occasions with his raw pace and eye for goal. He is at a perfect age to continue to improve and I am looking forward to working with him this season."
Elliott will wear squad number 14 at the Jakemans Community Stadium.