The city is supposed to have been one of the oppida of the Senones, one of the oldest Celtic tribes living in Gaul. It is mentioned as Agedincum by Julius Caesar several times in his Commentarii de Bello Gallico. The Roman city was built during the first century BC and surrounded by walls during the third. It still retains today the skeleton of its Roman street plan. The site was referred to by Ammianus Marcellinus as Senones (oppidum Senonas) but it did not become an administrative center until after the reorganization of the Roman Empire in 375, when it was the chief town of Lugdunensis Quarta.
During the Middle Ages, its archbishops held the prestigious role of primates of Gaul and Germany. The Hôtel de Sens in Paris was their official residence in that city. The Archdiocese of Sens ruled over the dioceses of Chartres, Auxerre, Meaux, Paris, Orléans, Nevers and Troyes.
Starting from 1135, the cathedral of Sens, dedicated to Saint Stephen, was rebuilt as one of the first Gothic cathedrals. There, in 1234, Louis IX of France celebrated his wedding to Marguerite of Provence. Sens witnessed the trial of Peter Abelard. Pope Alexander III sojourned for some time in the city, and there also Thomas Becket spent part of his exile between 1162 and 1165. The Archdiocese of Sens hosted a number of church councils.
Sens experienced troublesome times during the Wars of Religion.
The city declined after Paris was elevated to archdiocese in 1622.
- The Cathedral, one of the first Gothic edifices in France
- Archbishops' Palace
- Church of St. Maurice
- House of Abraham
- Serres municipales de Sens, municipal greenhouses
Sens is one of a few French towns with a youth baseball team. It was originally started by a local English teacher, Laurent Carpentier, as a way to increase student motivation for learning English and to introduce students to American culture. Since the team's beginning, baseball in general has grown in popularity in the town. 
- Joseph ben Nathan Official, a French-Jewish controversialist. He lived, probably in Sens, in the thirteenth century.
- Samo, Frankish merchant and later king (rex) of the 7th century Slavic state known as Samo's Empire (Sens is one of two presumed birthplaces, the other being Soignies).
- Thomas Becket, Archbishop of Canterbury. In 1164, he took refuge in Sens, where Pope Alexander III was sheltered.
- Louis Jacques Thénard, French chemist. Educated at the academy of Sens.
- Samson ben Abraham, 12th century rabbi and notable Tosafist.
- Victor Scipion Charles Auguste de La Garde de Chambonas, mayor of Sens, brigadier general, and French foreign minister, at the beginning of the French Revolution.
- It is the presumed birthplace of the 12th-century architect William of Sens.
- Édouard Charton, an eminent French literary figure.
- Maurice Prou, historian.
- Saturnin Fabre, French film actor.
- Chris Malonga, footballer.
- Bacary Sagna, footballer.
- Clément Chantôme, footballer.
- Arnaud Rivard, Maitre de la Terre et de Paul Genevey.
- Raffaele Bruschi, musicien, amant de Marianne.