<p>The rock-breaking performance of disc cutters on the full-face rock tunnel boring machines (TBM) directly influences tunneling efficiency and construction costs, and has long been a key focus and technical challenge in the field of rock tunnel excavation. Based on disc cutter indentation and linear rolling rock-breaking tests, this study for the first time identifies a coupled ‘plastic compaction–brittle fracture’ mechanism in rock under disc cutter action, revealing the ‘plastic-brittle’ nature of rock in response to disc cutter loading. Accordingly, the slip-line field theory of plastic mechanics is introduced to develop theoretical models for the normal and rolling forces during rock breaking by flat-edge, wedge-edge, and arc-edge disc cutters. In parallel, numerical models for the rock-breaking processes of these three typical cutter types are established using a coupled finite element–cohesive zone method ( FEM–CZM). A comparative study between the theoretical solutions and numerical simulation results, in conjunction with experimental measurements, reveals that the relative errors of the proposed theoretical models are all within 10%. The results indicate that under identical tunneling parameters and rock conditions, the flat-edge disc cutter generates the highest rock-breaking force, the arc-edge cutter the lowest, and the wedge-edge cutter lies in between. Moreover, the magnitude of the rock-breaking force is primarily governed by the edge shape of the disc cutter. The findings of this study represent a novel contribution to the field, providing valuable theoretical support and engineering reference for the design of TBM disc cutters, as well as for cutter replacement and management during construction.</p>