This work presents the constitutive modeling for the tear fracture and its mechanical behavior of rubber with filler particles. A continuum mechanics-based analytical model is developed here to predict the mechanical properties of rubber with a suitably added filler. The model is then validated with the experimentalresults of the chloroprene and nitrile butadiene rubbers filled with different volume fractions of carbon black and carbon nanoparticles, respectively. Further, the tear fracture phenomenon of the filled rubber is modeled adopting a well-known Griffith criterion based on the developed constitutive model. The aimed tear fracture phenomenon is focused on a particular fracture test of mode-III, namely the trousers test, where two legs of a cut specimen are pulled horizontally apart. The results show that the fracture toughness of the filled rubber increases with the rise in the volume of filler particles. In general, the developed model will be helpful to the researchers in characterizing the material behavior of tires and other rubber-like materials.