Chirac has served as president since 1995 and his widely expected decision to stand aside marks the end of an era for France, clearing the way for a new generation of politicians.
''I will not seek your backing for a new mandate,'' the 74-year-old said in a televised address to the nation.
Chirac will perhaps be best remembered outside France for his denunciation of US policy in Iraq and his determination to maintain his country's leading role in international affairs.
But on the domestic front he introduced few meaningful reforms and leaves behind a difficult legacy for his successor, with the French economy underachieving and social tensions simmering in deprived suburbs.
Opinion polls have indicated for months that Chirac would have been trounced if he had run for a record third mandate in the April/May election, but he had kept a resolute silence over his plans to avoid being regarded as a lame duck president.
All the three leading contenders to succeed Chirac -- Nicolas Sarkozy of the ruling UMP party, Socialist Segolene Royal and centrist Francois Bayrou -- are in their 50s and all have pledged to break with the politics of the past 25 years.
The last survivor of a political generation that started out in the postwar governments of General Charles de Gaulle, Chirac's career was dogged by allegations of corruption, which he always denied, dating from his 18 years as mayor of Paris.
OUT OF TOUCH During his reign, Chirac ended compulsory military service, played an important role in ending the Yugoslav civil war in the 1990s and was the first president to acknowledge that France's World War Two Vichy regime had assisted in the Holocaust.
However, he was regarded as increasingly out of touch on domestic issues and suffered a major defeat when voters rejected the planned European constitution in 2005, pushing the European Union into crisis and weakening his international standing.
After building a power base in the Paris town hall, Chirac succeeded a dying Francois Mitterrand in 1995 and crushed far-right leader Jean-Marie Le Pen to be re-elected in 2002.
He infuriated Washington with his vocal opposition to the 2003 war in Iraq and embodied the forces scornfully dismissed by former US Defence Secretary Donald Rumsfeld as ''Old Europe''.
In Europe itself, he held tightly to the traditional Franco-German alliance, particularly with former German Chancellor Gerhard Schroeder, and refused to surrender the lavish subsidies enjoyed by the French farming sector.
Charismatic and clever, Chirac was brilliant on the campaign trail but had a less certain touch in office. At one point he had the worst popularity ratings of any French president but his support has climbed of late as his retirement neared.
His mandate ends on May 17 and it is not clear if he will still play a role in public life after that, or whether he will withdraw quietly to his rural retreat in Correze with his wife Bernadette.
''There is without doubt a life after politics. Until death,'' he said in a television interview last month.
Reuters DKS VP0048