Treatment of posttraumatic stress symptoms (PTSSs) and facilitation of posttraumatic growth (PTG) are two encouraging areas of research, yet little is understood about the relationships between dispositional mindfulness, PTSSs, and PTG. The aim of the present study was to investigate whether PTSSs is correlated with PTG among breast cancer patients in China and explore the role of mindfulness in this relationship. A sample of 202 Chinese breast cancer patients voluntarily participated in the study by completing a set of questionnaires. The results revealed that PTSSs were significantly positively correlated with PTG. Structural equation modeling showed that mindfulness did not moderate but mediated the relation between PTSSs and PTG. These findings indicate that breast cancer patients with higher mindfulness may recover from PTSSs through a different process. Posttraumatic growth may not be the only positive indicator of posttraumatic individuals.