Sidelined by a back injury since the World Cup, O'Connell said after the game: "It's great to be back. We got the win and I came out of it injury free. It was a great day and very enjoyable even if I only played for 35 minutes or so.
"I probably didn't do much, it was all about getting through the game injury free. The back came through it fine," said the second row, who added that he will wait until Sunday morning before declaing himself fit for selection for Munster's crucial Heineken Cup tie against Clermont Auvergne next weekend.
"I wasn't that worried about my back as the physios have done a great job for me," he said.
O'Connell said that after the disappointment of the World Cup what he missed most was not being able to train.
"I enjoy training and the one thing that was needed after the World Cup to get rid of the disappointment was to get back training. I couldn't do that and have only been involved in contact training for two weeks. I had to rest my back and let it recover slowly.
"The conditions were ideal to test my back with a lot of picking and driving, a lot of defending around the side of the rucks and a lot of scrums."
Concluding, the Munster captain said: "It was great to come back for my first game with Young Munster and great to get the win."
Ballynahinch 5 Belfast Harlequins 17
Thomond 11 Highfield 12
Young Munster 12 Buccaneers 10
Connemara v Ards (Match postponed)
Banbridge 27 Waterpark 0