According to Deadline, the team behind the Showtime series was keen to reintroduce the lesbian mothers of Fitch (Peter Facinelli).
The women were played by Blythe Danner and Swoosie Kurtz in the first season, but Danner was reportedly unable to return because she is working on a film.
Light has now allegedly signed up to replace her in the show.
Light previously starred as Claire Meade in Ugly Betty and plays Elizabeth Donnelly in Law & Order: Special Victims Unit.
The third season of Nurse Jackie is expected to begin on Showtime early next year.
> 'Wire' star signs up for 'Nurse Jackie'