The Australian comedienne, who is best known for her role in Kath and Kim, said that she does not need professional support any more after shedding 25kg and dropping six dress sizes since becoming the face of the programme in early 2009.
Szubanski told the Herald Sun: "That niggling worry that used to be there sabotaging everything I did... is gone. As part of my ongoing health journey, Jenny Craig has provided some fabulous and practical tools and great support. It was never intended to be forever."
She also revealed that Bridesmaids star Rebel Wilson will be taking over as Jenny Craig's ambassador, saying: "I wish Rebel Wilson health and happiness. Go girl."
Earlier this year, Szubanski revealed that she feels a "sense of pride" since losing weight, saying: "I strongly believe that if you don't have your health, you don't have anything. The whole thing for me about losing weight is, yes, you can wear fantastic clothes but it really is about health, improving your fitness and your enjoyment of life."
She has also admitted that she finds it "intimidating" being a "role model" because she thinks of herself as "a bit of a flake".