The New Jersey native, 27, joins the Red Bulls having most recently played for Columbus Crew SC, where he was on the roster earlier this season but made no MLS regular season appearances in 2017.
"Dilly is a veteran player, and our staff is very familiar with him," said Red Bulls sporting director Denis Hamlett in a team statement. "We've been able to have him in training for a few weeks and we've liked what he has shown. He brings attacking quality and experience to our roster, and we expect him to contribute moving forward."
In his MLS career, which began in 2010 with Columbus after being drafted out of Rutgers University, Duka has made 138 MLS regular season appearances (12 goals, 14 assists) and four MLS Cup Playoff appearances (one goal). All told, Duka has played for Crew SC (2010-12, 2016), the Chicago Fire (2013-14) and the Montreal Impact (2014-15) in his professional career.
"I'd like to thank the organization for the opportunity," said Duka. "I'm here to give 100 percent every day, and to help contribute in any way I can. The Red Bulls organization is first class and I see every day that every player is hungry for team success."
"We are pleased to add Dilly," said Red Bulls head coach Jesse Marsch. "We knew he was a talented, quality player and he has shown well in his time here. He's also a veteran of the league that we think improves our roster both on game day and in training. We look forward to integrating him into our team."