Deken had written a little-known volume of devotional poetry by the time she met Betje Wolff in 1776. The next year, following the death of Wolff's husband, the two set up house together and began collaborating on fiction. With their third book, Sara Burgerhart, they changed the direction of Dutch writing. By developing the epistolary technique, which had been introduced by Samuel Richardson in England, Deken and Wolff produced a realistic novel of subtle characterizations that was free of sentimentality and unnatural motivations. Deken's contribution to the plot was her experience, as a girl, of orphanage life and domestic service.

Further though less notable collaborations in the epistolary style followed, including De historie van den heer Willem Leevend, 8 vol. (1784–85; “The History of Mr. William Leevend”), and De historie van mejuffrouw Cornelia Wildschut, 6 vol. (1793–94; “The History of Miss Cornelia Wildschut”).

During the Prussian invasion of 1788, Deken and Wolff moved to Trévoux, Fr., where they lived for 10 years. Their book Wandelingen door Bourgogne (1789; “Strolling Through Burgundy”) related their impressions of the French countryside.

Although Deken wrote an additional four volumes of instructional verse, she is chiefly remembered for her association with Wolff.