Benefit finding is a concept that refers to finding positive changes or benefits through negative experiences from stressful life events. The present study aimed to develop a new intervention program to facilitate benefit finding for people with mental illness and examine its feasibility and preliminary efficacy from pilot data. We hypothesized that participants who joined the group-based intervention program would show progress in benefit finding, personal recovery, and well-being, as well as alleviated psychiatric symptoms and functional impairment, compared to participants in the control group. The participants in the intervention group joined in a new program which focuses on (1) cognitive–behavioral stress management and (2) own experiences, including what was found or realized through their lives since the onset of mental illness. The program used a workbook comprised of eight 90-min sessions, with one held every week. Twenty-four were found eligible and provided informed consent to participate in the study. About 46% were males, and the average age was 42.5 years. Around 63% were diagnosed with schizophrenia. We did not find significant differences over time by groups. However, medium to large effects in each scale or at least one subscale (i.e., benefit finding, personal recovery, subjective well-being, and psychiatric symptoms and functional impairment) were observed. Future studies with more participants from various settings would be necessary to exactingly examine the effectiveness of the intervention program.