Purpose <p>Although there is a test to measure kickboxing-specific anaerobic power, there is no valid and reliable test to specifically evaluate the upper-body endurance capacity of kickboxers. In the present study, we determine the test–retest reliability and discriminant validity of a novel Kickboxing Progressive Maximal Punch Test (KPMPT).</p> Methods <p>Eighteen Elite (28.7 ± 5.4&#xa0;years, 72.5 ± 9.3&#xa0;kg, and 1.70 ± 0.08&#xa0;m) and 14 Trained (26.7 ± 5.7&#xa0;years, 72.8 ± 9.3&#xa0;kg, and 1.69 ± 0.08&#xa0;m) kickboxers performed two KPMPT on different days. The KPMPT consisted of executing successive strokes, in which one stroke corresponded to two punches (jab and straight punch). The KPMPT started at 30 strokes.min⁻¹ (i.e., 60 punches.min⁻¹) and increased 1 stroke.min⁻¹ (i.e., 2 punches.min⁻¹) until exhaustion.</p> Results <p>Test–retest reliability scores (intraclass correlation coefficient, typical error of measurement, standard error of measurement, smallest worthwhile change, minimal detectable change, and coefficient of variation) ranged from good to excellent for time to exhaustion, maximum heart rate, and percentage of age-predicted maximum heart rate. The area under the Receiver Operating Characteristic (ROC) curve for time to exhaustion was considered excellent (0.982, <i>p</i> &lt; 0.001), with an optimal cutoff point identified at 645&#xa0;s, a sensitivity of 89%, and a specificity of 100% to discriminate the Elite from the Trained group. Trained athletes also presented higher coefficients and intercepts for the logarithm adjustment of the heart rate-time curve than Elite athletes (<i>p</i> &lt; 0.001).</p> Conclusions <p>The KPMPT identifies similar results on different days and detects differences in upper-body endurance capacity between Elite and Trained kickboxers. Thus, the KPMPT seems to be a simple, reliable, and valid test for evaluating the upper-body endurance capacity of kickboxers.</p>