The American actress will reprise her role as Detective Olivia Benson for the 13th series of the US TV show, which stars Christopher Meloni, Richard Belzer and Dann Florek, as well as Ice-T, who plays Detective Odafin 'Fin' Tutuola.
Speaking at NBC's Television Critics Association panel, network head Robert Greenblatt said: "There were some rumors of her dropping down, and bringing in new cast members. But Mariska is there in every single episode, and it's my goal to see that continues past this season.
"In the past couple years, to my understanding, she's lightened her load a little bit. The show's going into its 13th year, so I think it's not unreasonable to think she might want to lighten her workload.
"There might be a day every couple of weeks she's not working, but I don't think you'll notice [her missing]."
The show is set to premiere in September with plenty of new characters promised.