Jacques Edouard Guerlain (French pronunciation: [ʒak ɡɛʁlɛ̃]; 7 October 1874 – 2 May 1963) was a French perfumer, the third and most famous of the Guerlain family. One of the most prolific and influential perfumers of the 20th century, over eighty of Guerlain's perfumes remain known, though certain estimates suggest he composed some four hundred. Among his greatest fragrances are L’Heure Bleue (1912), Mitsouko (1919) and Shalimar (1925). Though his work earned him universal renown, a considerable fortune and honours such as that of Chevalier of the Legion of Honour, Guerlain avoided public attention, never once granting an interview. As a result, relatively little is known of his creative process or personal life.

Many of his major works are archived in their original form at the Osmothèque, donated by Thierry Wasser on behalf of Guerlain in 2014.

Jacques Guerlain, the second child of Gabriel and Clarisse Guerlain, was born in 1874 in the family villa in Colombes. He was educated in England, in keeping with family tradition, and then in Paris at the École Monge where he studied history, English, German, Greek and Latin. His uncle, perfumer Aimé Guerlain, was childless, and thus trained Jacques from the age of sixteen as his apprentice and successor. In 1890 Jacques created his first perfume, Ambre. He then interned in the organic chemistry laboratory of Charles Friedel at the University of Paris, before being officially employed in the family business in 1894. He experimented widely in both cosmetics and fragrance, perfecting a method for perfuming ink while publishing with Justin Dupont on the subject of various essential oils. Meanwhile, he composed his earliest works such as Le Jardin de Mon Curé (1895). In 1897 he assumed joint ownership of his family's company, shared with his brother, Pierre, and father. For two years, Jacques and Pierre exchanged the responsibilities of manager and chief perfumer, until Jacques assumed the latter role in 1899. During this period, Jacques composed several perfumes, including Tsao Ko (1898), his first perfume to reference the Orient, a dominant theme in his oeuvre.

At the Exposition Universelle in 1900, Jacques Guerlain presented the leathery floral Voilà Pourquoi J'Aimais Rosine in tribute to Sarah Bernhardt (born Rosine Bernardt), a friend of the Guerlain family. The grimly named Fleur Qui Meurt (1901) was a novel experiment with violet (created in perfumery via synthesis), a common accord in Guerlain's oeuvre. This was followed by a pair, Voilette de Madame (1904) and Mouchoir de Monsieur (1904), the latter being one of Guerlain's few masculines and largely akin to his uncle's Jicky (1889).

In 1905 Guerlain married Andrée Bouffet, a Protestant from Lille, and did so according to Protestant law, thereby suffering excommunication from the Catholic Church. Their first child, Jean-Jacques, was born the following year, as Guerlain finished Après l'Ondée (1906), his first major commercial success. This perfume, translated as "After the Rains" and described at its release as "melancholy" by La Liberté, was a continuation in Guerlain's experiments with notes of heliotrope and violet. Due to affordable synthetics, this accord was popular in mainstream perfumery, though Guerlain's treatment, incorporating anisic aldehyde, eugenol and large quantities of orris root, was considered exemplary by many, including perfumer Ernest Beaux.

Kadine, released in 1911, referenced a concubine in a sultan's harem, another Oriental subject. Though Guerlain never visited Asia, his fascination with the East led him to collect Oriental art; celadon and Blanc de Chine china featured in his ever-expanding collection decorating his apartment by the Parc Monceau at 22 Rue Murillo. An aesthete of diverse tastes, Guerlain purchased Nevers faience, and from Rouen manufactories alongside furniture by André Charles Boulle and Bernard II van Risamburgh (since acquired by the Louvre), paintings by Francisco Goya, Édouard Manet and Claude Monet (including The Magpie) and antique books.

Guerlain's passion for Impressionism and its distinctive effets de soir are thought to have influenced L’Heure Bleue (1912), meaning "The Blue Hour". An apt metaphor for Paris at the end of the Belle Époque and the beginning of World War I, Guerlain's grandson and successor Jean-Paul Guerlain explains it thus:

On the eve of the outbreak of World War I, Guerlain released Le Parfum des Champs-Elysées (1914), a chocolaty floral, to inaugurate the boutique at 68 Avenue des Champs-Élysées. It was sold in a turtle-shaped bottle allegedly referencing the boutique's tortoiselike architect, Charles Mewès.