法国对美国独立战争的干涉导致国家破产。在财政改革一再失败之后，路易十六被说服召开三级会议——由三个等级：教士、贵族和平民组成的国民代表会议。1789年5月三级会议的成员们在凡尔赛宫召开会议，但是对于采取何种投票制度的讨论走进了死胡同。进入6月，第三等级，在其他两个等级的成员们的声援下，宣布自己为法国的国民议会，宣誓直到法国制定出一部宪法之前决不解散，并在7月成立了国民制宪议会。在同一时间巴黎人民进行起义，1789年7月14日攻占了著名的巴士底狱。
在此时议会想建立君主立宪制，在随后的两年内通过了包括《人权和公民权宣言》、废除封建制度和根本上改变了法国与罗马关系的各种法律。起初国王对这些变化安然接受，受到人民的普遍欢迎，但随后在外国入侵的威胁下反对王权的要求变得越来越强烈，国王被剥夺了权力，决定和家人一同溜走。他被人认了出来带回巴黎。1793年1月，被判叛国罪而处死。
1792年9月20日，国民公会废除了君主制，宣布法国为共和国。由于战事紧急，国民公会组建了公共安全委员会，由雅各宾俱乐部的马克西米连·罗伯斯庇尔领导，作为国家的行政机关。在罗伯斯庇尔领导下委员会实行了恐怖统治，在巴黎有4 0000人被处决，主要是贵族和被革命法庭审判的人，证据往往非常单薄。在其他地区，反革命叛乱被强力镇压。该政权在热月政变（1794年7月27日）中被推翻，罗伯斯庇尔被处决。接手的政权中止了恐怖，放松了罗伯斯庇尔的比较极端的政策。
拿破仑·波拿巴是法国在革命战争中最杰出的将领，征服了意大利的大部分，迫使奥地利人屈膝求和。1799年他从埃及返回，在雾月政变（11月9日）中推翻了政府，代之以执政府，自任第一执政。1804年12月4日，在一次暗杀行动失败后，他把自己加冕为皇帝。1805年拿破仑计划入侵英国，但是英国和俄罗斯与奥地利重新结成了第三次反法同盟，迫使他将注意力转到欧洲大陆，同时将占优势的英国海军舰队从英吉利海峡引出的计划失败，法国在10月21日决定性的特拉法尔加海战中战败，入侵英国的希望破灭。1805年12月2日，拿破仑在奥斯特利茨战役中击败了数量占优的奥地利-俄国联军，迫使奥地利推出反法同盟（见普莱斯堡条约）并解散了神圣罗马帝国。1806年第四次反法同盟建立，1806年10月14日拿破仑在耶拿-奥尔斯塔特战役中击败普鲁士，并穿越德国在1807年6月14日弗里德兰战役中击败俄军。蒂尔西特条约在法俄之间瓜分了欧洲，并创建了华沙公国。
1812年6月12日拿破仑以70万人的大陆军入侵俄国。在精心布置的斯摩棱斯克战役和博罗金诺战役胜利之后，拿破仑占领了莫斯科，却发现城市已经被撤退的俄军付之一炬。他被迫撤军，在撤退的路上受到哥萨克的骚扰、疾病和饥饿的侵袭。只有2万人在战后活了下来。至1813年局势转为对拿破仑不利。在1813年10月莱比锡战役中败于七国联军之后，他在六日战役和巴黎沦陷之后被迫退位，在枫丹白露条约下被放逐到埃尔巴岛。他在1815年3月1日回到法国（见“百日王朝”），建立起一支军队，但不出意料地在1815年6月18日在滑铁卢战役中败于英国和普鲁士军队。
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.