Background The experiences of teenagers with cancer are related to falling ill, receiving treatment, and the way they exist in the world. The understanding of the meaning of teenagers coexisting with cancer must be placed in the social context with the teenagers at the core. Objective By using an interpretive ethnographic research method, this study applied the body perception view of Merleau-Ponty to how teenagers with cancer understand self through the body in a social and cultural context. Methods Participant observation and individual semistructured interviews of 18 teenagers diagnosed with cancer were conducted over a 20-month period. Results The illness experience of teenagers undergoing chemotherapy was described as self-integration. Five themes emerged: Boundary ambiguity of body, medical equipment as part of the body, confined body space, from self-dissociation toward self-integration, and healing power formed by self and others. Conclusion In the face of the adjustments of body disorder, the teenagers with cancer initiated motility of the body, self-displacement, and integration in order to regain control of the body. Implications for Practice The provision of correct disease knowledge to strengthen teenagers' understanding and their sense of mastery of their bodies throughout the participation in their cancer treatment is essential. Discussions on making decisions, self-management, and social identification are related to the relationship between body and self as well as between healthcare and otherness. Providing culture and social sensitivity support systems and resources to teenagers and families can strengthen them to face the disease and promote positive healing.