The 2009 French Open was a tennis tournament played on outdoor clay courts. It was the 108th edition of the French Open, and the second Grand Slam event of the year. It took place at the Stade Roland Garros in Paris, France, from May 24 through June 7, 2009.

Rafael Nadal and Ana Ivanovic were the defending champions. Both failed to defend their titles, losing to Robin Söderling and Victoria Azarenka in the fourth round, respectively. Nadal's loss to Söderling was his first defeat in the tournament since debuting in 2005, and would remain his sole loss at the tournament until the 2015 French Open. Söderling proceeded to defeat Nikolay Davydenko and Fernando González on his way to the final, where he was defeated by Roger Federer. By winning the French Open, Federer equalled Pete Sampras' then-record of 14 Grand Slam titles, and completed his Career Grand Slam by winning the tournament; he had lost the previous three finals to Nadal. Svetlana Kuznetsova, the runner-up to Justine Henin-Hardenne in 2006, was the women's champion this year. She defeated World No. 1 Dinara Safina in the final, avenging a semi-final loss to the same opponent in 2008.

Entering the tournament, four-time champion Rafael Nadal was unbeaten in French Open singles matches, having won every match and tournament since his debut in 2005. His victory against Russian Teymuraz Gabashvili in the second round on May 27 was his 30th consecutive win, breaking the record for the longest French Open winning streak by a man or woman, held by Chris Evert, who won 29 consecutive matches. Nadal extended the record to 31 consecutive matches by beating Lleyton Hewitt on May 29.

In his fourth round match on May 31, Nadal was defeated by World No. 23 Robin Söderling in four sets, 2–6, 7–6, 4–6, 6–7. The upset result ended Nadal's French Open winning streak at 31 matches. Söderling had never previously reached the fourth round of any Grand Slam tournament, and had never previously beaten Nadal in three attempts, although he had taken him to five sets at Wimbledon in 2007. Söderling proceeded to reach the final, defeating Nikolay Davydenko in straight sets and Fernando González in five sets before losing to Roger Federer in his first Grand Slam final appearance.

Of the upset result, former three-time French Open champion Mats Wilander stated that "Everybody's in a state of shock, I would think. At some point, Nadal was going to lose. But nobody expected it to happen today, and maybe not this year. Now it's a matter of: There's a tournament to be won." Nadal would begin another streak the next year, and did not lose another match at the tournament until the 2015 French Open, when he lost to Novak Djokovic.

After nearly a year out of the sport due to a serious shoulder injury which forced her to miss the 2008 Beijing Olympics, the 2008 US Open and her Australian Open title defence, Maria Sharapova, who started at World No. 53 by the time the entry list was released, then plummeted to as low as World No. 126 during her time away from the sport, entered the tournament ranked World No. 102 at the start of the tournament, and surprised many by reaching the quarter-finals, where she was defeated 6–0, 6–2 by Dominika Cibulková (Sharapova had to defend a match point at 0–6, 0–5 down). Sharapova, unseeded at a Grand Slam for the first time since 2003, had won all of her first four matches in three sets.

Roger Federer won the finals, against Robin Söderling to finally win the French Open tournament for the first time in his career, after he was beaten in three previous finals by Nadal. With this win, he completed his career Grand Slam, titles in all four Grand Slam tournaments in his career. He became the third male player in the Open era (after Rod Laver and Andre Agassi) and sixth male player in tennis history overall to accomplish the feat.

Andrey Golubev of Kazakhstan became the first male winner at this year's French Open. French favourites Julie Coin and Mathieu Montcourt enjoyed safe passages through to the second round, but compatriot Mathilde Johansson was unable to use the crowd's advantage, falling to Vitalia Diatchenko 2–6, 6–2, 10–8. Lleyton Hewitt came from 2 tiebreak sets down, taking a third set tiebreak and eventually the match over the 26th seeded Croat Ivo Karlović, winning 6–7(1), 6–7(4), 7–6(4), 6–4, 6–3, to cause the first upset of a seed in the tournament. Karlovic set the new record for the greatest number of aces in the match, serving 55, but couldn't find a way to win. French wildcard Josselin Ouanna came from two sets to one behind to defeat Marcel Granollers, 7–5, 2–6, 3–6, 7–6(2), 6–1. However, Amélie Mauresmo lost to Anna-Lena Grönefeld 6–4, 6–3, to add to her history of early-round exits at Roland Garros. However, seventh seed Gilles Simon recovered from a tight clash with Wayne Odesnik, 4–6, 7–5, 6–2, 4–6, 6–3. Former French Open champion Gastón Gaudio made a disappointing start to his grand slam comeback, losing in straight sets to Radek Štěpánek 6–3, 6–4, 6–1.