Phillips has arrived on-loan from Manchester City.
The midfielder said: “This is a day I’ve been waiting a number of weeks for now and I’m very happy to be here.
“I’ve had some great conversations with players I know here and also with the Manager, who I have obviously heard a lot about, and I’m excited to be here and be part of his team, playing how he likes to play the game.
“The conversations with Kieran McKenna and Mark Ashton have been really good and I followed Ipswich’s season closely last year, so I know the journey the Club has been on and it’s a great story which I’m now excited to be a part of.
“I want to play as many games as possible, enjoy playing football again and help the team win as many games as possible in the Premier League.”
Town Manager Kieran McKenna added: “We are very happy to have Kalvin here and he is a fantastic signing for the football club.
“He is of course a high-calibre, experienced midfielder who has played at the highest levels of the game, in both club and international football.
“He’s had a fantastic career up until this point and we believe he is going to be a big addition to the group.
“Kalvin has much to offer us in terms of his qualities both on and off the ball, and he is a really humble and likeable character. He has been a key member of a newly-promoted team in the Premier League before and of course made a big impression for Leeds United during that period.
“Like all players who come here we want to try and help them improve, whether that’s a younger player or one with more experience. That’s a big part of our culture and we’re sure Kalvin can make some big steps with us to help him and the Club have a really positive season.”