Purpose <p>To investigate the differences in the physical, physiological, and cognitive parameters among different chronotypes in endurance athletes.</p> Methods <p>A randomized crossover study was conducted on 51 (22.6 ± 2.8 years) endurance athletes to assess the impact of chronotype on performance across different times of day. The participants were divided into Morning (<i>n</i> = 25) and evening (<i>n</i> = 26) groups based on their chronotype. Outcome measures included physical performance (aerobic capacity, body composition), physiological responses (cardiac autonomic function, sleep quality), and cognitive function (coping ability and mental resilience, and executive function). Assessments were performed during both morning and evening sessions with a washout period of 48&#xa0;h.</p> Results <p>Evening-type athletes exhibited significantly higher Yo-Yo test and VO₂max performance during evening sessions (<i>p</i> &lt; .01), while morning-types showed greater resting metabolism, muscle mass, and coping capacity (<i>p</i> &lt; .01). HRV demonstrated a significant time-of-day effect (<i>p</i> &lt; .01), confirming diurnal modulation of autonomic activity. Sleep quality (PSQI) did not differ significantly between groups (<i>p</i> &gt; .05).</p> Conclusion <p>Chronotype and time of day significantly influence endurance athletes’ performance and physiological readiness. Aligning training and testing schedules with individual chronotypes may enhance both performance outcomes and recovery efficiency, emphasizing the importance of chronobiological considerations in athletic planning.</p>