He joins the club from Cymru Premier side The New Saints, where he has been playing his football since 2016 following a move from Scottish side Dumbarton.
During that time, the 34-year-old has won five Cymru Premier titles, four JD Welsh Cups and three Nathaniel MG Cups. He was also previously named in the Welsh Premier League Team of the Year.
Routledge started his youth career with Liverpool before joining Wigan Athletic, where he was promoted to the senior side.
He then spent time with the likes of Hamilton Academical and Stockport County, but will now bolster Marine's midfield ranks as Neil Young's side look to continue their promotion push.
“I’m really looking forward to meeting up with the lads and trying to help have a good end to the season," he said.
"Hopefully I can help as best as I can for the team.”
Photo credit: The New Saints