<p>Adolescents who experience bullying victimization are at elevated risk of long-term health problems, yet research has primarily focused on trait-level explanations and has overlooked the day-to-day processes that may drive this vulnerability. This study examined whether bullying victimization – a threat to adolescents’ basic psychological needs (autonomy, competence, relatedness) – sensitizes daily-life experiences, as reflected in (a) a direct association of bullying victimization with greater psychological need frustration and subjective stress and (b) bullying victimization modulating the association between psychological need frustration and subjective and physiological stress (i.e., momentary cortisol, next-day cortisol awakening response, total daily average cortisol). In total, 231 Belgian adolescents (<i>M</i>_<i>age</i> = 13.43 years; <i>SD</i>_<i>age</i> = 0.38; 45% female) took part in the study. Over the course of 1 year, adolescents reported their bullying victimization every 6 months. During a 14-day experience-sampling period, participants then reported their psychological need frustration and subjective stress 5 times per day, on the first 4 days of which salivary cortisol was collected. Higher levels of bullying victimization were associated with greater daily need frustration. Additionally, there was weak evidence that the within-person association between subjective stress and next-day cortisol awakening response was stronger for bullied adolescents – a pattern that emerged only in unadjusted models. Exploratory analyses suggested that victimized adolescents were particularly sensitive to relatedness frustration, showing, for example, a stronger within-person association between relatedness frustration and subjective stress. These findings highlight the need for interventions that target bullied adolescents’ psychological needs, given their heightened sensitivity to daily stressors.</p>