Among the new faces are highly-rated Leinster number eight Jamie Heaslip, who has won three caps, and his provincial colleague Bernard Jackman.
Jackman has profited after Munster hooker Jerry Flannery was yesterday suspended for the entire tournament for stamping while on Heineken Cup duty.
With Rory Best fit after recovering from his ankle injury, Jackman is likely to feature on the bench when O'Sullivan unveils his starting line-up to face Italy on Tuesday.
Jackman looks set to be joined by Munster second row Mick O'Driscoll, who has beaten off the challenge of Leinster's Leo Cullen to secure his place in the squad.
An update on Paul O'Connell's back injury is expected soon - surgery would force him to miss the entire RBS 6 Nations - so Donncha O'Callaghan and Malcolm O'Kelly are the first choice locks.
Munster prop Tony Buckley is included, supplying back-up for starting front rows John Hayes and Marcus Horan, while Leinster winger Robert Kearney also features.
With Shane Horgan struggling because of a knee injury - the Leinster veteran starts Ireland A's game against England Saxons next Friday - Kearney could go straight into the XV for Italy.
Should O'Sullivan opt for experience instead, Geordan Murphy of Leicester will be handed the number 14 jersey.
Kearney has been selected ahead of Tommy Bowe, whose Ulster team-mate Neil Best is a high-profile omission from the 22.
The other position in doubt is scrum-half where O'Sullivan must choose between Peter Stringer and Eoin Reddan - with the latter in pole position.
"The match 22 selection for the Italy game was made on the basis of form," said O'Sullivan.
"While the response of all of the squad over the last week has been excellent, there were some tight calls to be made.
"This will be even harder to do next week when we decide the final selection for the game."
O'Sullivan will remain loyal to the players that misfired so spectacularly at the World Cup for as long as possible.
To an extent the Ireland coach is caught between a rock and a hard place, weighing up the pressing need to uncover the next generation of Test players with the win-at-all-costs approach essential if he is to keep his job.
A poor performance in the RBS 6 Nations would conclude O'Sullivan's six-year reign as Ireland boss and the 49-year-old is under immense pressure.
The precarious nature of his position is no more apparent than in the Irish Rugby Football Union's decision to delay making the new appointments of team manager, backs coach and sports psychologist until after the tournament.
Mindful that a new head coach might want different personalities on his management team, the IRFU are waiting to see how the RBS 6 Nations unfolds before acting.
But O'Sullivan is confident his first choice Ireland team remain a force to be reckoned with as he fights to restore his battered reputation.
"It's not rocket science to see where it went wrong at the World Cup," he said.
"We didn't play enough rugby in the build-up to the tournament and we were in a difficult group which we struggled to get out of.
"But we didn't become a bad rugby team overnight. The Six Nations is an opportunity to prove that."