The 24-year-old, who is also a former Sky Blues trainee, has passed a medical and will join the club on July 1.
O'Donovan joined the Black Cats in 2006 following a prolific spell at Cork City, but made only 17 appearances for the club before enjoying a number of loan spells, including at Hartlepool towards the end of last season, where he scored nine goals in 15 appearances.
Boothroyd said: "As soon as I arrived, I saw that we needed competition for places in attack and Roy is chomping at the bit to be a success here.
"His opportunities at Sunderland were restricted but there is no doubting he can mark his mark on the Championship.
"He follows Gary McSheffrey by returning to the club he was at during his youth, and we're steadily building the foundation of a strong, driven squad."