The 30-year-old has played 12 times for Rovers this season but has not featured in any of their three games under new boss Henning Berg.
Orr will stay at Portman Road until the end of January, and he has spoken out about his relief at joining up with Mick McCarthy's men.
He told the East Anglian Daily Times: "There were a few things going on in the upper echelons of the club at Blackburn and I wanted to get out on loan.
"Once I heard of Ipswich's interest I was really keen to come down here. Thankfully we've managed to get something sorted and I'm absolutely delighted.
"I know Ipswich well from playing here a number of times. It's a big club and it's an honour to be here."