Ceramic matrix composites have immense applications in the aerospace, aircraft, automobile, and defense industries. Carbon fiber-reinforced ceramic matrix composites (C/SiC) are used for critical applications due to their superior properties. However, these materials have stringent heterogeneity, anisotropy, and varying thermal properties that affect machining quality and process efficiency. Developing a cutting force prediction model and analyzing machining parameters is essential. In this study, a mechanistic-based feed direction cutting force prediction model for rotary ultrasonic profile milling of C/SiC composites is developed and validated experimentally. The practical and simulated results closely matched each other. The mean error and the standard deviation were recorded at 1.358% and 6.003, respectively. The parametric sensitivity analysis showed that the cutting force decreased with increased cutting speed, whereas the same increased with increased feed rate and depth of cut. The proposed cutting force for rotary ultrasonic profile milling of C/SiC composites can be applied to predict cutting forces and optimize the machining process.