Mock interviews are crucial in the UPSC preparation process as they simulate real interview conditions, allowing candidates to practice and refine their communication skills. They provide an opportunity for aspirants to receive constructive feedback on their responses, body language, and overall presentation. This practice enables candidates to build confidence and address weaknesses before the actual interview. Furthermore, engaging in mock interviews can help aspirants develop a better understanding of current affairs and relevant issues, enhancing their readiness for the final evaluation.