The 26-year-old has enjoyed a meteoric rise in the intervening period, joining Lorient from Tours in June 2009 and then moving to Arsenal a year later after only a single season in the French top flight.
Following a shaky start at the Emirates, including a red card on his competitive debut at Liverpool, he has blossomed into one of the most refined central defenders in the English game.
A booking for Philippe Mexes against Sweden on Tuesday opened the door to the France starting line-up for Koscielny, who said he had been too intently focused on the match to grasp the ramifications. "I didn't think about his suspension, I was concentrating on the result," Koscielny said earlier this week. "It was Olivier [Giroud] who told me.
"I feel good. I need to get a bit of rhythm, but I played (in the 2-0 friendly win) against Serbia. There won't be any worries. There are all the ingredients for an unforgettable match. Lots of players dream of playing their first game at a EURO against the defending champions."
Born in 1985 in Tulle, Koscielny played for a number of local sides at junior level before joining Guingamp in 2003. He made his professional debut with the club in 2004, but played mainly as a right-back until his move to third-tier Tours in 2007, when his displays at centre-back contributed to the club's promotion to the second division.
His second season with the club, in 2008/09, saw him selected in the Ligue 2 team of the season and a move to Lorient swiftly followed, but Arsenal were already tracking the progress of the swift and slender defender.
After his debut season in Ligue 1 confirmed his potential, Arsene Wenger swept in to take him to north London, where his elegance on the ball has enabled him to adapt smoothly to Arsenal's signature style.
He is also an excellent reader of the game, and Chelsea's David Luiz was the only centre-back to match him for interceptions in the Premier League last season. International recognition followed in February 2011, when he received a first call-up from France coach Laurent Blanc.
A Polish grandfather meant that he was also eligible to play for Poland, but Koscielny made it clear from the outset that he was only interested in representing France. "I've not thought about it too much, but in my mind, I'm French," he said in July 2010.
He made his debut in a 1-0 friendly win over USA last November, but he will go into Saturday's game against Spain with only three international appearances to his name. It is scant experience for an assignment of such magnitude, and Koscielny has spent little time on the pitch with his new centre-back partner Adil Rami.
"We've played a match and a half together," said Koscielny, who filled in as a holding midfielder in the 4-0 friendly win over Estonia earlier this month. "It went well. We try to communicate a lot on the pitch. We know each others' qualities. Each of us will do our own job."
Spain's swarming forwards will test Koscielny's concentration to the full, but given the pace of his progress in recent years, the prospect seems unlikely to faze him.