Florentius is a saint of the Roman Catholic Church and a

bishop of Vienne The Archbishopric of Vienne, named after its episcopal seat in Vienne in the Isère département of southern France, was a metropolitan Roman Catholic archdiocese. It is now part of the Archdiocese of Lyon. History The legend according to whi ...

from the late 4th century,Metropolitan Archdiocese of Vienne
GCatholic.org. dated by his attendance at the Council of Valence in 374. Florentius' feast day is locally celebrated on 3 January. Florent or Florentinus is mentioned in the list of bishops of Vienne produced by archbishop

Ado of Vienne Ado of Vienne ( la, Ado Viennensis, french: Adon de Vienne; died 16 December 874) was archbishop of Vienne in Lotharingia from 850 until his death and is venerated as a saint. He belonged to a prominent Frankish family and spent much of his early ...

(799-875) in his ''Chronicle'', according to which however he lived in the previous century during the reigns of the emperors

Volusianus Gaius Vibius Volusianus (died August 253) was a Roman emperor from 251 to 253, ruling with his father Trebonianus Gallus. After Emperor Decius and his son and co-ruler Herennius Etruscus died in battle in June 251, Trebonianus Gallus was el ...

(251-253) and

Gallienus Publius Licinius Egnatius Gallienus (; c. 218 – September 268) was Roman emperor with his father Valerian from 253 to 260 and alone from 260 to 268. He ruled during the Crisis of the Third Century that nearly caused the collapse of the empi ...

(253–260) as the 8th bishop of Vienne, and was martyred:

Florentinus, too, bishop of Vienna, distinguished himself by his way of life and his teaching; he remained in place until the reigns of Gallienus and Volusianus, and, in exile, accomplished his martyrdom."Florentinus quoque, episcopus Viennensis, uita et doctrina emicuit; mansit ad Galieni et Volusiani imperium, exiliatusque martyrium compleuit." Adon de Vienne, ''Chronique'', VI, col. 86D4.3, in ''Vienne dans les textes grecs et latins'', Gérard Lucas, pp.247–270
online version

References

Bishops of Vienne 4th-century Christian saints 4th-century bishops in Gaul {{bishop-stub