This review article focuses on the Mullins effect in tough elastomers and gels, specifically nanocomposite gels, double-network hydrogels, and multi-network elastomers. The Mullins effect, characterized by stress softening during loading and unloading cycles, is a significant phenomenon in these materials. The article revisits experimental observations and discusses recent developments in constitutive models, emphasizing novel damage mechanisms and network representations. It highlights the challenges in accurately predicting multiaxial data and the need for anisotropic and multiaxial modeling. The review also covers various phenomenological models and introduces new damage models, such as those developed by Wang et al., Tang et al., Lavoie et al., Bacca et al., and Vernerey et al. These models account for different aspects of the Mullins effect, including pullout effects, pseudo-elastic behavior, progressive damage, and recovery effects. Additionally, the article explores new network models, such as Zhao's interpenetrating polymer network model and Mao et al.'s model considering bond deformation, which provide more accurate descriptions of the complex mechanical behaviors of these materials. The review concludes with a discussion on the limitations and future directions in modeling the Mullins effect in tough elastomers and gels.This review article focuses on the Mullins effect in tough elastomers and gels, specifically nanocomposite gels, double-network hydrogels, and multi-network elastomers. The Mullins effect, characterized by stress softening during loading and unloading cycles, is a significant phenomenon in these materials. The article revisits experimental observations and discusses recent developments in constitutive models, emphasizing novel damage mechanisms and network representations. It highlights the challenges in accurately predicting multiaxial data and the need for anisotropic and multiaxial modeling. The review also covers various phenomenological models and introduces new damage models, such as those developed by Wang et al., Tang et al., Lavoie et al., Bacca et al., and Vernerey et al. These models account for different aspects of the Mullins effect, including pullout effects, pseudo-elastic behavior, progressive damage, and recovery effects. Additionally, the article explores new network models, such as Zhao's interpenetrating polymer network model and Mao et al.'s model considering bond deformation, which provide more accurate descriptions of the complex mechanical behaviors of these materials. The review concludes with a discussion on the limitations and future directions in modeling the Mullins effect in tough elastomers and gels.