The defender was a free agent after leaving Stoke City and had been training with Ipswich. The League One side have now confirmed the signing of Ward along with Oli Hawkins and goalkeeper David Cornell.
The 34-year-old has seven years of Premier League experience, after spells with Wolves and Burnley.
Former Republic of Ireland manager, Mick McCarthy signed Ward from Bohemians in 2007 and he went on to spend seven years with Wolves. In 2014 he moved to Burnley and spent seven years at Turf Moor before signing for Stoke City.
He also has 50 international caps to his name, his last appearance was in the 4-1 Uefa Nations League defeat to Wales in Cardiff in September 2018.
The Dubliner announced his retirement from international football in March 2019.
Ward also featured in the European Championship finals in 2012 and 2016.
"I'm delighted to have signed," Ward said.
"At this stage of my career I just wanted to find a project that really excited me. Ipswich is a massive club, a club that should really be higher in terms of league status. That's what we'll look to do this year. The ambition is to get promoted.
"I actually scored my first goal in England when I moved over here [for Wolves]. I've always enjoyed playing here, there's always a really good atmosphere, the town really gets behind the club.
"Hopefully we can give them something to cheer about."
