<p>The aim of this study is to develop a self-help intervention based on acceptance and commitment therapy; to examine the effect of the self-help intervention on the depression, anxiety, stress, and psychological flexibility levels of university students; and to examine their experiences. In this study, we used a mixed explanatory basic design. In the quantitative part of the study, we used a 2 (experimental and control group) x 3 (pretest-posttest and follow-up test) experimental design. The participants consisted of 47 university students. The experimental group received a 7-week guided self-help intervention based on acceptance and commitment therapy, whereas the control group received no intervention. Participants completed a Personal Information Form, Depression Anxiety and Stress Scales-42, and Acceptance and Action Questionnaire-II. We conducted semi structured interviews to examine the experiences of participants in the experimental group. We analyzed the data using an independent samples <i>t</i> test, repeated measures ANOVA, one-way ANCOVA, and content analysis. According to the study’s results, we found guided acceptance and commitment therapy-based self-help intervention decreased students’ depression, anxiety, and stress levels and increased their psychological flexibility levels. The qualitative findings of the study revealed four general concepts: “difficulties experienced while implementing the intervention program,” “prominent parts of the intervention program,” “benefits of the intervention program,” and “components of the intervention program.” We discussed self-help experiences in light of the relevant academic literature.</p>