Speaking at the team hotel in Killiney, O'Gara said of his appointment: "It's an unbelievable honour, I'm very, very proud. It's a huge occasion for me. My parents and my brothers will be proud of me too and that's something I don't take for granted.
"It's a huge challenge. It's a big position in Irish sport, to captain the Irish rugby team, and it's something I'm looking forward to doing.
"I don't know how many times I'll do it so I intend to make the most of this and hopefully put in a performance that the country is proud of."
O'Sullivan had no qualms about handing the captain's armband to O'Gara instead of his Munster colleague O'Connell.
"The call was made on the basis that Paul has been out for a while and has only one game of Six Nations rugby under his belt this season," explained the Irish boss.
"I want him to focus on leading the pack and his own display. Paul was happy with the rationale behind the call.
"Ronan has captained Munster this year and I see it as spreading of the load. He's an experienced player who is well capable of organising the team. He's a senior guy."
O'Gara revealed that O'Connell, whom he regards as 'a natural leader and a very close friend', has given the number 10 his full backing to make a success of his stint as captain and drive Ireland to victory at Twickenham.
"I talked to Paul, of course. He was the first person up to congratulate me. I think the key issue with Paul is that he's just returning from a long term injury and he probably felt that he needed another one or two games at this level under his belt.
"I was his deputy (as captain) at Munster but when Paul comes back he's the main man and that's exactly how it will go. The two of us are very close and we'll support each other and that's the key thing," he added.
"Just because I'm named captain, his role won't change. If Paul is named captain in the future, I don't think my role will change. The two of us have immense pride in how the team performs."
O'Gara has gained valuable experience this season by captaining Munster throughout their successful run in the Heineken Cup pool stages.
He admitted: "I've really enjoyed captaining Munster this year. I suppose I take the responsability very personally. It's important to me that I make sure we deliver a performance and that's the key to this weekend."
With nothing but pride on the line, many fans and pundits will view this Ireland-England game as nothing more than a dead rubber, but O'Gara does not see it that way.
"I don't think the people that sit down in front of their TV on Saturday will view it like that. I think Ireland against England traditionally gets the highest viewing figures. It will make the people happy if we can beat England at Twickenham.
"If we win this weekend I don't think it will have been a disappointing campaign (for us). If we underperform at the weekend it will be. But it's really all about this weekend now and I think fellas are excited about that.
It's huge, this weekend is a pivotal game. I know we've underperformed in some games but if we get a win this weekend I think it will be very important to the coaching staff and the bunch of players that are here."