Despite the evidence of unmet support needs among young people who have lost a parent to cancer, only a few support group initiatives have been reported. This observational prospective study explored the psychosocial well-being of young people who participated in support groups at a Swedish specialist palliative care setting. On three occasions, 29 participants, aged 16–28 years, answered questionnaires covering characteristics of the participants, circumstances of the losses, psychosocial well-being of the young people, and their own assessment of the support groups. The support groups attracted mostly young women who were often unprepared for the loss. The living arrangements differed between younger and older participants; however, the loss-related variables did not differ. Significant positive changes were found regarding a sense of meaning in their future life and life satisfaction. The helpfulness of the group was assessed as high/very high and the group brought a valuable fellowship with others in a similar situation. Universality and beneficial interactions were reported and strengthened psychosocial well-being developed over time. This change, according to the young people themselves, may be attributed to the group support. The findings are useful for planning interventions to support young people in bereavement in order to enhance their psychosocial well-being.