This work presents an approach to simulate laser cutting of ceramic substrates utilizing a phase field model for brittle fracture. To start with, the necessary thermoelastic extension of the original phase field model is introduced. Here, the Beer–Lambert law is used in order to model the effect of the laser on the substrate. The arising system of partial differential equations—which comprises the balance of linear momentum, the energy balance, and the evolution equation that governs crack propagation—is solved by a monolithic finite-element scheme. Finally, the influences of the laser power and the initial groove size on the manufactured work piece are analyzed numerically in simulations of a laser-cutting process.