The 31-year-old right-back has not featured under new Boro boss Aitor Karanka and signs on at Portman Road until the end of the season.
Richardson, who only joined Boro in the summer, has found a long-time admirer in Town boss Mick McCarthy who twice almost signed him when in charge of Sunderland and Wolves.
McCarthy has his man now, though, and he should be in contention to make his debut against former club Leeds on Tuesday.
Richardson follows Richie Smallwood, Adam Reach and Luke Williams out on loan this week.
James Tarkowski has credited Sean Dyche for his England call-up, admitting he would have found it 'difficult' to represent Poland.
Jordan Hugill says he is desperate to prove he is ready to play a bigger part in West Ham's battle against relegation.
Harry Maguire says he's discovered his best form at Leicester this season as he seeks to cement his spot in England's World Cup squad.