This study aimed to analyze the influence of the competitive level and weight class on technical performance and physiological and psychophysiological responses during simulated MMA fights. Twenty MMA male athletes were divided into four groups: heavyweight elite (HWE; n = 6), lightweight elite (LWE; n = 3), heavyweight professional (HWP; n = 4), and lightweight professional (LWP; n = 7). All athletes performed four simulated fights of three 5-min rounds with a 1-min rest interval. Each fight was recorded using a video camera to analyze offensive and defensive actions. Moreover, the following measures were made: heart rate (before and after each round), blood lactate concentration (before and after the fight), readiness state (before each round), and the rate of perceived exertion (RPE) (after each round). The main findings were: i) LWE athletes applied more offensive touches than LWP athletes; ii) HWP athletes presented higher heart rate values than LWP athletes after the first round; however, LWP athletes presented greater heart rate changes than HWP athletes from the first to the second round; iii) no differences existed between groups in blood lactate concentration and readiness state; and iv) HWP and LWP athletes presented higher RPE values than LWE athletes in the first and third rounds; however, LWE athletes presented greater RPE changes than HWE, HWP, and LWP athletes from the first to the second and third rounds. This study shows that LWE athletes apply more offensive touches than LWP athletes during simulated MMA fights. Moreover, lightweight athletes tend to increase their physiological demand as the combat evolves, which is also reflected in their RPE.