But whilst acknowledging that he is far from the finished article, the 24-year-old now sees himself as a much more rounded player compared to the one who made his debut as a replacement against Italy two years ago.
"I think I am becoming more comfortable at the level. It took me a while. I probably wasn't fit enough, probably 18 months ago, but I feel more comfortable with my game now," he said.
"Physically, I feel much better as well. I've had time to develop and I have been very lucky to have some great strength and conditioning guys around me as well, who have taken care of me and held me together."
O'Mahony's leadership qualities were endorsed by Les Kiss last summer when he appointed the Corkman as Ireland captain for their North America tour, while the following month he was installed as Munster's skipper for the current season.
The firebrand flanker has used that increased level of responsibility to improve his own game, tidying up his discipline and maintaining a relentless work-rate at the breakdown and other key areas.
So much so that all of his 22 caps have come in Ireland's last 22 Tests, with his run of 16 successive starts showing just how much of an influential figure he is becoming.
His 6ft 3in, 17 stone frame was employed to very good effect in the set piece battle against England, winning seven lineout throws in a 100% return.
O'Mahony was unable to finish the Twickenham defeat due to a hamstring strain. The Ireland camp issued an update on Thursday, stating that the injury is 'improving' and that 'it is hoped he will commence running over the weekend'.
Speaking earlier in the week, Ireland head coach Joe Schmidt said: "Peter O'Mahony has no respect for his body, he's had a fantastic series so far.
"There is a little bit of blood (on the hamstring scan), but no tear so those things normally clear up quickly. It's a case of managing Pete this week so that he can train next week."
Ireland's first Six Nations loss ended their Grand Slam and Triple Crown ambitions, but O'Mahony is confident they can make their chances count in the upcoming games against Italy (home) and France (away).
"There's no need to panic. We didn't become a bad team overnight. We're playing good rugby and putting ourselves in good positions to put some more points on the board.
"The sooner we realise that - the fact that we're putting ourselves in those positions - then the sooner we'll start taking them."
He added: "The teams that you see doing that (closing out wins) are probably very experienced teams who have been there. To most extents we should be nearly there ourselves.
"We should be finishing out those games (New Zealand and England) and it's disappointing that we're not because we have an experience there.
"We have talked about the consistency in games that we should be finishing off. At times we are and at times we're not. That's probably our inconsistency coming back to bite us. It's certainly something we've talked about stamping out of our game."
Ireland took on England with a team boasting 724 Test caps. O'Mahony was one of seven players aged between 22 and 24 who saw action during the round 3 fixture, with centre Brian O'Driscoll the elder statesman at 35.
Next Saturday's match against Italy will be a huge occasion for O'Driscoll as he overtakes former Wallaby George Gregan (139 caps) as the world rugby's most-capped international player of all-time.
In what will be his final home game for Ireland at the Aviva Stadium, O'Driscoll will also become the most-capped player in RBS 6 Nations history - eclipsing Ronan O'Gara's previous record of 63 tournament appearances.
O'Mahony does not feel that those milestones will distract O'Driscoll and company from their aim of defeating Italy and maintaining their lead at the top of the Championship table.
"We are professional enough that it won't affect us. It is obviously a big occasion for Brian and it would be great for him to finish his last Test in Ireland on a winning side, but the rest of us now need to be a bit selfish - and him too.
"There is a job to be done at the weekend and he is more professional than anyone who has put on an Irish jersey, so I don't think there is an issue there."
O'Mahony was just 10 years of age when O'Driscoll ran in his famous hat-trick of tries against France back in the inaugural Six Nations Championship in 2000.
The young back rower has hailed O'Driscoll's lasting influence on this generation of Irish players, noting how he has adapted his game to combat his advancing years.
"He was the first superstar of Irish rugby and always very exciting to watch. You wouldn't even have to go looking for him. You would see him on the TV screen so often, because he was carrying so much ball, breaking lines.
"He was probably a bit raw at the time. Video analysis wasn't the same and defences weren't the same so he was making big, long breaks and it was very impressive to watch.
"Not much has changed, really. Last weekend (against England) he was running over guys. He used to run around them, now he goes over the top of them."