The 26-year-old signed for Dynamos after a two-year stint with the Belgian club Waasland Beveren, according to a release.
"I am very excited about coming to India and playing in the ISL. The club management has shown a lot of faith in me, and have given me a chance to play for them this season. I intend to prove to them and the fans that I can add to the team's performance, and I hope to win the ISL in my very first season," Addy said in the release.
The Ghanaian international has played for Portuguese club FC Porto in 2010-12. His debut for the senior national team came in 2008 and he has made 21 appearances for his country.
Dynamos' head coach Gianluca Zambrotta said, "David is a strong defender with great natural talent who will add power to our defence. He has spent time in Africa and Europe, and also holds great experience having played in the Europa League."
"We welcome David to the Delhi Dynamos FC squad. He has played for various European clubs, and performed well in the Europa League. We are looking forward to working with him this season, and help him maximise his potential under the guidance of Gianluca." said Dynamos' Chief Technical Officer Vishnu Madhu.