Mock interviews play a significant role in UPSC interview preparation by simulating the real interview environment. They help candidates practice their responses to typical questions, improving their confidence and communication skills. In mock interviews, candidates receive constructive feedback on their body language, articulation, and subject knowledge, allowing them to make necessary adjustments. This practice helps in reducing anxiety and prepares candidates to handle unexpected questions with ease. Ultimately, mock interviews refine a candidate's overall presentation and interpersonal skills, which are vital in the actual interview.