Early in her career van Keulen made drawings, stories and poems for the magazine Propria Cures.

[1] In 1986, van Keulen won the Zilveren Griffel award for her first children's book Tommie Station (1985).

[1][2] A few years later, she received a Vlag en Wimpel award in 1993 for her book Meneer Ratti.

[1] Some of van Keulen's work has been published under the pseudonyms Josien Meloen and Constant P.

[2] Van Keulen was also lijstduwer for the Party for the Animals during the European Parliament election in the Netherlands in 2004 as well as in 2014.