Pierre Waldeck-Rousseau was born in Nantes, Loire-Atlantique. His father, René Waldeck-Rousseau, a barrister at the Nantes bar and a leader of the local republican party, figured in the revolution of 1848 as one of the deputies returned to the Constituent Assembly for Loire Inférieure. The son was a delicate child whose eyesight made reading difficult, and his early education was therefore entirely oral. He studied law at Poitiers and in Paris, where he took his licentiate in January 1869. His father's record ensured his reception in high republican circles. Jules Grévy stood sponsor for him at the Parisian bar. After six months of waiting for briefs in Paris, he decided to return home and joined the bar of St Nazaire early in 1870. In September he became, in spite of his youth, secretary to the municipal commission temporarily appointed to carry on the town business. He organized the National Defence at St Nazaire, and himself marched out with his contingent, though they saw no active service owing to lack of ammunition, their private store having been commandeered by the state.

In 1873, following the establishment of the Third Republic in 1871, he moved to the bar of Rennes, and six years later was returned to the Chamber of Deputies. In his electoral program he had stated that he was prepared to respect all liberties except those of conspiracy against the institutions of the country and of educating the young in hatred of the modern social order. In the Chamber he supported the policy of Léon Gambetta.

The Waldeck-Rousseau family was strictly Catholic in spite of its republican principles; nevertheless Waldeck-Rousseau supported the Jules Ferry laws on public, laic and mandatory education, enacted in 1881 - 1882. In 1881 he became minister of the interior in Gambetta's grand ministry. He further voted for the abrogation of the law of 1814 forbidding work on Sundays and fast days, for compulsory service of one year for seminarists and for the re-establishment of divorce. He made his reputation in the Chamber by a report which he drew up in 1880 on behalf of the committee appointed to inquire into the French judicial system.

He was chiefly occupied with the relations between capital and labour, and had a large share in securing the recognition of trade unions in 1884. He became again minister of the interior in the Jules Ferry cabinet of 1883 - 1885, when he gave proof of great administrative powers. He sought to put down the system by which civil posts were obtained through the local deputy, and he made it clear that the central authority could not be defied by local officials. Waldeck-Rousseau also deposed the 27 May 1885 act establishing penal colonies, dubbed "Law on relegation of recidivists", along with Martin Feuillée. The law was supported by Gambetta and his friend, the criminologist Alexandre Lacassagne.

Waldeck-Rousseau had begun to practise at the Paris bar in 1886, and in 1889 he did not seek re-election to the Chamber, but devoted himself to his legal work. The most famous of the many noteworthy cases in which his cold and penetrating intellect and his power of clear exposition were retained was the defense of Gustave Eiffel in the Panama scandals of 1893.

In 1894 he returned to political life as senator for the department of the Loire, and next year stood for the presidency of the republic against Félix Faure and Henri Brisson, being supported by the Conservatives, who were soon to be his bitter enemies. He received 184 votes, but retired before the second ballot to allow Faure to receive an absolute majority. During the political crisis of the next few years he was recognized by the Opportunist Republicans as the successor of Jules Ferry and Gambetta, and at the crisis of 1899 on the fall of the Charles Dupuy cabinet he was asked by President Émile Loubet to form a government.

After an initial failure he succeeded in forming a coalition cabinet of "Republican Defense", supported by the Radical - Socialists and the Socialists, which included such widely different politicians as the Socialist Alexandre Millerand and the General de Galliffet, dubbed the "repressor of the Commune". He himself returned to his former post at the ministry of the interior, and set to work to quell the discontent with which the country was seething, to put an end to the various agitations which under specious pretences were directed against republican institutions (far-right leagues, Boulangist crisis, etc.), and to restore independence to the judicial authority. His appeal to all republicans to sink their differences before the common peril met with some degree of success, and enabled the government to leave the second court-martial of Alfred Dreyfus at Rennes an absolutely free hand, and then to compromise the affair by granting a pardon to Dreyfus. Waldeck-Rousseau won a great personal success in October by his successful intervention in the strikes at Le Creusot.

With the condemnation in January 1900 of Paul Deroulède and his nationalist followers by the High Court the worst of the danger was past, and Waldeck-Rousseau kept order in Paris without having recourse to irritating displays of force. The Senate was staunch in support of Waldeck-Rousseau, and in the Chamber he displayed remarkable astuteness in winning support from various groups. The Amnesty Bill, passed on 19 December, chiefly through his unwearied advocacy, went far to smooth down the acerbity of the preceding years. With the object of aiding the industry of wine producing, and of discouraging the consumption of spirits and other deleterious liquors, the government passed a bill suppressing the octroi duties on the three "hygienic" drinks -- wine, cider and beer. The act came into force at the beginning of 1901.

But the most important measure of his later administration was the Associations Bill of 1901. Like many of his predecessors, he was convinced that the stability of the republic demanded some restraint on the intrigues of the wealthy religious bodies. All previous attempts in this direction had failed. In his speech in the Chamber, Waldeck-Rousseau recalled the fact that he had tried to pass an Associations Bill in 1882, and again in 1883. He declared that the religious associations were now being subjected for the first time to the regulations common to all others, and that the object of the bill was to ensure the supremacy of the civil power. The royalist bias given to the pupils in the religious seminaries was undoubtedly a principal cause of the passing of this bill; and the government took strong measures to secure the presence of officers of undoubted fidelity to the republic in the higher positions on the staff. His speeches on the religious question were published in 1901 under the title of Associations et congregations, following a volume of speeches on Questions societies (1900).

As the general election of 1902 approached all sections of the Opposition united their efforts under the Bloc des gauches, and the name of Waldeck-Rousseau served as a battle-cry for one side, and on the other as a target for abuse. The result was a decisive victory for republican stability. With the defeat of the machinations against the republic, Waldeck-Rousseau considered his task ended, and on 3 June 1902 he resigned office, having proved himself the "strongest personality in French politics since the death of Gambetta." He emerged from his retirement to protest in the Senate against the construction put on his Associations Bill by Émile Combes, who refused in mass the applications of the teaching and preaching congregations for official recognition.

His speeches were published as Discours parlementaires (1889); Pour la République, 1883 - 1903 (1904), edited by H Leyret; L'État et la liberté (1906); and his Plaidoyers (1906) were edited by H Barboux. See also H Leyret, Waldeck-Rousseau et la Troisième République (1908).