St Ledger has been named in the Ireland squad for the World Cup play-off clashes with France (Nov 14 & 18).
He won his first cap against Nigeria in May and has been ever-present since.
St Ledger has warned France's superstars they are in for a battle if they are to squeeze past the Republic of Ireland into next summer's World Cup finals.
Sean St Ledger: "It's a tough draw and probably not one we would have chosen.
"They have a team full of stars and some of the world's best players - but they finished second in their group for a reason.
"I'm sure there will be a great atmosphere in both legs, but the support we will get at Croke Park will be brilliant and the noise our fans make will be invaluable.
"They should be two unbelievable games to play in.
"Of course, France are the favourites and I'm sure they will expect to win.
"But the Italy game gives us a lot of belief that we can do well against a really top side.
"As a nation and as a team, we always seem to rise to the occasion, so we can go into both legs with confidence.
"We are very organised under Mr Trapattoni and we will have a game plan to beat them.
"I seem to have said this a lot recently, but this will be the biggest game of my life so far.
"Getting to the World Cup would be the pinnacle, so the two games against France will be massive. I look forward to it."
Elsewhere in the draw, Portugal were paired with Bosnia-Herzegovina, Greece will meet Ukraine and Russia and Slovenia will fight it out for the remaining place.