The 23-year-old, who also counts Rotherham, Macclesfield and Grimsby among his former clubs, spent last season in the north west with Bury.
Marshall revealed former Millers team-mate and Shrimps fans' favourite Kevin Ellison was an influence on his decision to join Jim Bentley's squad.
"The gaffer really sold the club to me when I met him and I can't wait to get going," said Marshall on Morecambe's official website.
"I played with Kevin Ellison at Rotherham and he said this was a great club to be at and everything I have seen so far points to that.
"I had a disappointing season with Bury and I am just looking to start playing regularly again and enjoy my football and I am really looking forward to pre-season training and meeting the lads next week."