The experiences of inner harmony and ethical sensitivity among late adolescents during the COVID-19 pandemic depend on the interplay of perceptive factors, personal resources and cognitive and stress mechanisms. Using a sample from Poland, the present study examined the relationships between the perceptions of COVID-19 and the Light Triad and the characteristics of inner harmony and ethical sensitivity from the mediational perspective of meaning-making and perceived stress. Three hundred and sixteen late adolescents were recruited in the cross-sectional study. They filled in questionnaires measuring the perception of COVID-19, the Light Triad, meaning-making, stress, inner harmony and ethical sensitivity, from April to September 2020. The perception of COVID-19 was negatively related to ethical sensitivity, whereas the Light Triad was positively related to inner harmony and ethical sensitivity. Perceived stress and meaning-making mediated the relationships between the perceptions of COVID-19, the Light Triad and the characteristic of inner harmony. Perception processes and the Light Triad dimensions directly influence ethical sensitivity, as well as indirectly affect inner harmony through meaning-making processes and perceived stress. This noticeably highlights the vital role played by meaning structures and emotional reactions in the experience of inner peace and calmness.