The English winger has put pen to paper on a one year contract that will see him continue his journey with the club.
The 34-year-old has already played 260 times since joining them from Newcastle United in 2011.
Routledge spoke to the club's official website about the news and said: "I am going into my ninth season with Swansea City. Just saying that puts a big smile on my face.
"It was an emotional night at the Liberty in our final home game. There were a few tears because I didn't know if that was the last time I would play at the Liberty.
"But now I can look forward to preparing for next season."