Pearlitic steels are widely used in the industry for their good balance between strength, ductility and machinability. Sometimes, the classical lamellar structure can degenerate in a so-called globular structure which may significantly affect the behavior of the steel. To our knowledge, no size sensitive model is available in the literature to predict their mechanical behaviors and work-hardenings. Inspired by their analogy with ferrite–martensite dual-phase microstructures, we propose a new microstructure-based law for globular pearlite. It describes the evolution of the dislocation density into ferritic grains which is enhanced by the presence of hard particles. The model is as a consequence sensitive to ferritic grain but also to coarse carbide sizes after globularization. The model has been calibrated on a conventional steel grade and appears to be a practical tool for microstructure design.