The Australia international was understandably nostalgic as he left Goodison Park, after eight superb years, in which he became a firm fan favourite.
"I also want to thank everyone at Everton, from the club to tremendous supporters," he told his new club's official website.
"It has been a privilege to be an Everton player for the past eight years and it was a very difficult decision to leave. I will always support Everton and I wish the club the best of luck in the future."
The New York Red Bulls, captained by former Arsenal legend Theirrry Henry, are top of the Eastern Conference, and the 32-year-old midfielder is desperate to help secure the team's first league title.
"I am very happy to start a new chapter of my career with the New York Red Bulls," added Cahill.
"As we have seen over the past few years, MLS has developed into a very competitive league with many talented players
"I am impressed with what the Red Bulls are trying to accomplish in MLS and within American soccer and I am looking forward to this new challenge. I will do everything I can to help bring New York its first MLS Cup."
General manager and sporting director Erik Soler shared Cahill's excitement, praising the arrival of the Australia international.
"We are absolutely thrilled to bring in a player of Tim's calibre to the Red Bulls," he stated.
"He is the technical, physical presence we have been looking to add in our team and he brings a wealth of experience to our club having played in some of the highest levels of international soccer.
"Tim is a proven leader both on and off the field and we believe that he can help us immediately in our quest to win the MLS Cup this season."