法國對美國獨立戰爭的干涉導致國破産。在財政改革一再失敗之，路易十六被說服召開三級會議——由三個等級：教士、貴族和平民組成的國民代會議。1789年5月三級會議的成員們在凡爾賽宮召開會議，但是對於取何投票制度的討論走進死同。進入6月，第三等級，在其他兩個等級的成員們的聲援下，宣佈自己為法國的國民議會，宣誓直到法國定出一部憲法之前决不解散，在7月成立國民憲議會。在同一時間巴黎人民進行起義，1789年7月14日攻占著名的巴士底獄。
在此時議會想建立君主立憲，在隨的兩年內通過包括《人權和公民權宣言》、廢除封建制度和根本上改變法國與羅馬關係的各種法律。起初國王對這些變化安然接受，受到人民的普遍歡迎，但隨在外國入侵的威脅下反對王權的要求變得越來越強烈，國王被剝奪權力，决定和人一同溜走。他被人認出來帶巴黎。1793年1月，被判叛國罪而處死。
1792年9月20日，國民公會廢除君主，宣佈法國為共和國。由於戰事緊急，國民公會組建公共安全委員會，由雅各賓俱樂部的馬西米連·羅伯斯庇爾領導，作為國的行政機關。在羅伯斯庇爾領導下委員會實行恐怖統治，在巴黎有4 0000人被處决，主要是貴族和被革命法庭審判的人，證往往非常單薄。在其他地區，反革命叛亂被強力鎮壓。該政權在熱月政變（1794年7月27日）中被推翻，羅伯斯庇爾被處决。接手的政權中止恐怖，放受不了羅伯斯庇爾的比較極端的政策。
拿破侖·波拿巴是法國在革命戰爭中最傑出的將領，服意大利的大部分，迫使奧地利人屈膝求和。1799年他從埃及返，在霧月政變（11月9日）中推翻政府，代之以執政府，自任第一執政。1804年12月4日，在一次暗殺行動失敗，他把自己加冕為皇帝。1805年拿破侖計入侵英國，但是英國和俄羅斯與奧地利重新結成第三次反法同盟，迫使他將註意力轉到歐洲大陸，同時將占優勢的英國海軍艦隊從英吉利海峽引出的計失敗，法國在10月21日决定性的特拉法爾加海戰中戰敗，入侵英國的希望破滅。1805年12月2日，拿破侖在奧斯特利茨戰役中擊敗數量占優的奧地利-俄國聯軍，迫使奧地利推出反法同盟（見普萊斯堡條約）解散神聖羅馬帝國。1806年第四次反法同盟建立，1806年10月14日拿破侖在耶拿-奧爾斯塔特戰役中擊敗普魯士，穿越德國在1807年6月14日弗德蘭戰役中擊敗俄軍。蒂爾西特條約在法俄之間瓜分歐洲，創建華沙公國。
1812年6月12日拿破侖以70萬人的大陸軍入侵俄國。在精心佈置的斯摩棱斯戰役和博羅金諾戰役勝利之，拿破侖占領莫斯科，卻現城市已經被撤退的俄軍付之一炬。他被迫撤軍，在撤退的路上受到哥薩的騷擾、疾病和饑餓的侵襲。衹有2萬人在戰活下來。至1813年局勢轉為對拿破侖不利。在1813年10月萊比錫戰役中敗於七國聯軍之，他在六日戰役和巴黎淪陷之被迫退位，在楓丹白露條約下被放逐到埃爾巴島。他在1815年3月1日到法國（見“百日王朝”），建立起一支軍隊，但不出意料地在1815年6月18日在滑鐵盧戰役中敗於英國和普魯士軍隊。
French intervention in the American Revolutionary War had bankrupted the state. After repeated failed attempts at financial reform, Louis XVI was persuaded to convene the Estates-General, a representative body of the country made up of three estates: the clergy, the nobility, and the commoners. The members of the Estates-General assembled in the Palace of Versailles in May 1789, but the debate as to which voting system should be used soon became an impasse. Come June, the third estate, joined by members of the other two, declared itself to be a National Assembly and swore an oath not to dissolve until France had a constitution and created, in July, the National Constituent Assembly. At the same time the people of Paris revolted, famously storming the Bastille prison on 14 July 1789.
At the time the assembly wanted to create a constitutional monarchy, and over the following two years passed various laws including the Declaration of the Rights of Man and of the Citizen, the abolition of feudalism, and a fundamental change in the relationship between France and Rome. At first the king went along with these changes and enjoyed reasonable popularity with the people, but as anti-royalism increased along with threat of foreign invasion, the king, stripped of his power, decided to flee along with his family. He was recognized and brought back to Paris. On 12 January 1793, having been convicted of treason, he was executed.
On 20 September 1792 the National Convention abolished the monarchy and declared France a republic. Due to the emergency of war the National Convention created the Committee of Public Safety, controlled by Maximilien Robespierre of the Jacobin Club, to act as the country's executive. Under Robespierre the committee initiated the Reign of Terror, during which up to 40,000 people were executed in Paris, mainly nobles, and those convicted by the Revolutionary Tribunal, often on the flimsiest of evidence. Elsewhere in the country, counter-revolutionary insurrections were brutally suppressed. The regime was overthrown in the coup of 9 Thermidor (27 July 1794) and Robespierre was executed. The regime which followed ended the Terror and relaxed Robespierre's more extreme policies.
Napoleon Bonaparte was France's most successful general in the Revolutionary wars, having conquered large parts of Italy and forced the Austrians to sue for peace. In 1799 he returned from Egypt and on 18 Brumaire (9 November) overthrew the government, replacing it with the Consulate, in which he was First Consul. On 2 December 1804, after a failed assassination plot, he crowned himself Emperor. In 1805, Napoleon planned to invade Britain, but a renewed British alliance with Russia and Austria (Third Coalition), forced him to turn his attention towards the continent, while at the same time failure to lure the superior British fleet away from the English Channel, ending in a decisive French defeat at the Battle of Trafalgar on 21 October put an end to hopes of an invasion of Britain. On 2 December 1805, Napoleon defeated a numerically superior Austro-Russian army at Austerlitz, forcing Austria's withdrawal from the coalition (see Treaty of Pressburg) and dissolving the Holy Roman Empire. In 1806, a Fourth Coalition was set up, on 14 October Napoleon defeated the Prussians at the Battle of Jena-Auerstedt, marched through Germany and defeated the Russians on 14 June 1807 at Friedland, the Treaties of Tilsit divided Europe between France and Russia and created the Duchy of Warsaw.
On 12 June 1812 Napoleon invaded Russia with a Grande Armée of nearly 700,000 troops. After the measured victories at Smolensk and Borodino Napoleon occupied Moscow, only to find it burned by the retreating Russian Army, he was forced to withdraw, on the march back his army was harassed by Cossacks, and suffered disease and starvation. Only 20,000 of his men survived the campaign. By 1813 the tide had begun to turn from Napoleon, having been defeated by a seven nation army at the Battle of Leipzig in October 1813. He was forced to abdicate after the Six Days Campaign and the occupation of Paris, under the Treaty of Fontainebleau he was exiled to the Island of Elba. He returned to France on 1 March 1815 (see Hundred Days), raised an army, but was comprehensively defeated by a British and Prussian force at the Battle of Waterloo on 18 June 1815.