The 28-year old USA midfielder has joined the Union permanently from Stoke City after a successful loan at PPL Park in 2014.
"I couldn't be happier to permanently return to Philadelphia and to play in front of our great fans. I believe in this team's future and am excited to be an integral part of that," said Edu, who made 31 appearances for Philly last term.
Additionally, Union technical director Chris Albright said: "Mo is an extremely important player to our organisation and we're excited that he will be in Philadelphia for the foreseeable future.
"We look forward to him helping lead us toward building a winning team."
Philadelphia Union (@PhilaUnion) January 14, 2015
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