<p><b>Abstract</b>—The effect of ultrasonic and microwave treatment of a monolayer formed by three-dimensional printing from prepregs reinforced with continuous carbon fiber on its strength under three-point bending was studied. Empirical strain–stress dependences were obtained, approximated with high accuracy by power functions. It was found that the electrophysical effect of both high and ultrahigh frequencies contributes to an increase in stresses in samples during their bending. In this case, the greatest efficiency (an increase of 54–72%) is noted at small deformations for samples exposed to a microwave electromagnetic field, including after preliminary ultrasonic treatment. With an increase in the magnitude of deformation, the efficiency of this method decreases. The effect of ultrasound is manifested to a much lesser extent and ranges from 8 to 15%, and it increases with increasing deformation. It is shown that the reason for the increase in the bending strength of composite prepregs is the increase in the uniformity of the binder structure and its density, as well as the “healing” of macrodefects in the form of discontinuities inherent in additive shaping technologies, which contributes to an increase in the number of reinforcing fibers involved in the process of load perception.</p>