This study investigated associations of early adolescents' (N = 190, median age = 12) subjectively experienced emotions and psychophysiological reactions in achievement situations. Self-reported questions assessed adolescents' experienced emotions. Additionally, adolescents' autonomic nervous system (ANS) reactions were recorded; skin-conductance response (SCR) and heart rate (HR) were used to measure sympathetic nervous system activity, and heart rate variability (HRV) was used to measure parasympathetic nervous system activity. The between-person-level results of multilevel modeling showed that increased HR was associated with higher levels of hope and fear and that decreased SCR was associated with a higher level of hopelessness. In turn, increased HRV was moderately associated with lower surprise at the within-person level. The results also showed that gender, hyperactivity, depressive symptoms, and cognitive ability moderated some of the associations between experienced emotions and physiological reactions. For example, high hyperactivity was related to stronger associations between SCR and hope and high depressive symptoms were related to a stronger association between HR and surprise. These findings enhance current understandings of connections between experienced emotions and psychophysiological reactions in achievement situations.