The former Tottenham Hotspur midfielder, who was transfer-listed during the summer, was named among the substitutes for Sunday's 2-1 win over Bradford City after four months out of the first team.
Ricketts believes that O'Hara's ability will make him a good addition to the side.
"He's effectively a new signing because he hasn't been with us all season," Ricketts told the Express & Star.
"He trained with us last Friday and this week and has undoubted quality, so it's just down to him to prove it and show to the Wolves fans the player he is."
O'Hara moved to Molineux from Tottenham in 2011.