The 27-year-old Irish forward links up with Aidy Boothroyd for a second time having been signed by the current Cobblers boss when he was in charge at the Ricoh Arena in the summer of 2010.
First-team chances were few and far between with the Sky Blues but whenever he was given an opportunity O'Donovan showed himself to be a willing runner, capable of making runs in between and behind defenders. Luck wasn't often on his side in terms of scoring goals but successive managers in Boothroyd, Andy Thorn and Mark Robins all praised O'Donovan's contribution.
Speaking this week after adding to the player to his options for the remainder of the season, Boothroyd said: "He is fit, athletic, mobile and he has an eye for goal. He will give us a different kind of threat to the other players we have at the club.
"I have worked with him before and he is a good character. I know what we are getting with Roy and I am very pleased we have been able to bring him in."