The former Lions captain has been on the sidelines since October after being forced to undergo surgery to fix a bulging disc in his back.
But he came through 40 minutes of the second string match with Leinster on Tuesday night without any ill effects, a huge boost for Munster and potentially the Lions.
"I'm delighted to be back and right now not feeling any ill effects," he said. "I'm happy with the way things went, although I was finding it tough towards the end - but I suppose that's to be expected if I'm trying to keep up with these young fellas.
"I'm injury free but I don't know about fit. It was very enjoyable. The lads played some great rugby. Luckily enough, it was a great day, a dry ball and that makes it harder on the lungs which is exactly what I needed.
"But it's just the intensity of getting up off the ground, of trying to be dynamic and get up and do it again five or six times in a row. That's something that's hard to replicate in training, especially in contact. So yeah, I was definitely blowing but I'm delighted. I don't feel any ill-effects now or anything. I feel good.
"The plan was to play today and see how I am tomorrow. And then I'll start planning again from there. The hope would be to be involved in the next couple of RaboDirect PRO12 games, first and foremost."
If he does prove his fitness in the next couple of weeks, O'Connell could be in contention to face Harlequins in the quarter-finals of the Heineken Cup on 7 April.
"The more games I can play the better. I think the Heineken Cup is definitely on for me. I'm available for selection anyway. The two lads (Donnacha Ryan and Donncha O'Callaghan) have been playing very well so we'll see what happens," he said.
Munster coach Rob Penney said: "The next 48 hours will determine if he plays for his club this weekend. If it is the right thing for Paul, then it's the right thing. We'll see how he backs up. I love the guys playing their club rugby when they can.
"I'm really pleased for him that he got through 40 minutes and looked vigorous.
"I was watching him closely around the contact area, the areas you need to be robust and he could have been potentially compromised but he didn't look like he was flinching at any time.
"He looks like he is on the mend and he is on track for a little bit more footie in the next week or so."