The experienced scrum-half knows the Exiles face a stiff challenge if they are to get off to a winning start next season as they take on perennial title challengers Saracens at Twickenham, where O'Leary was part of an Ireland team demolished 30-9 by England during the 2012 RBS 6 Nations.
But the 28-year-old is determined to prove his worth on-and-off the pitch for the Exiles, doing his best to help a new-look Irish side under returning head coach Brian Smith challenge for honours once more.
"I am excited about having a fresh start at London Irish, and I can't wait for the season to start," the double Heineken Cup-winner admitted, speaking at the launch of the J.P Morgan Asset Management Premiership Rugby 7s Series.
"I'm injury-free and keen to pull on the jersey and perform well for the team. I'm still getting to know the guys, which has been fun as all the lads seem like a good bunch.
"I am looking forward to our first game of the season in the London Double Header against Saracens.
"Saracens have become a very good side in the past two seasons and it will be a challenging opening game of the season. It will be a tough start but something the squad and also myself are really looking forward to.
"I do hope to be a crowd favourite, I want to put my own personality on things at the club and hopefully I can also help develop players on the training pitch.
"I moved to the club because of the Irish link and wanted to test myself in the Premiership.
"I spoke to Brian Smith and had a good chat about the club. He is very ambitious and his ambitions mirror my ambitions to achieve things at the club and better myself as a player."
J.P. Morgan Premiership Rugby 7s Series kicks off on 13 July at Harlequins, with rounds at Sale Sharks and Gloucester Rugby, and the final at Bath Rugby. Visit: www.jpmorgan7s.com to find out more.