Janssens may refer to:
- Abraham Janssens (circa 1567-1632), Flemish painter
- Cornelis Janssens van Ceulen (1593-1661), Dutch portrait painter
- Frans Alfons Janssens, (1865-1924), Belgian biologist who first described chromosomal crossover, calling the phenomenon chiasma
- Jan Willem Janssens (1762-1838), Dutch soldier and statesman
- Jean Janssens (footballer) (born 1944), Belgian football player
- Jean-Baptiste Janssens (1889-1964), twenty-seventh Superior General of the Society of Jesus
- Johann Hermann Janssens (1783-1853), Belgian theologian
- Mark Janssens (born 1968), retired Canadian ice hockey forward
- Patrick Janssens (born 1956), Belgian politician
- Victor Honoré Janssens (circa 1658-1736), Flemish painter