Background Reconstruction of lower extremity soft tissue defects is an exceptional surgical challenge, especially in multimorbid, elderly and severely ill patients with their thin and tense local soft-tissue conditions and increased perioperative risk. The distally based peroneus brevis muscle flap (DPBM), a local flap based on the muscular branches of the fibular artery, could pose a pragmatic solution. The objective of this study was to evaluate and quantify DPBM defect reconstruction in the lower leg, especially in elderly, multimorbid and severely ill patients. Material and Methods The DPBM as a surgical option in defect reconstruction in multimorbid, elderly, severely ill patients (inclusion criteria: at least 3 pre-existing comorbidities, patient age: at least 55 years, ASA status: at least III) was evaluated in a retrospective single-centre study from 01 April 2014 to 31 December 2019. The electronic SAP health records (EHR) were analysed according to 18 criteria, including patient details, extent of multimorbidity, defect characteristics, clinical outcome, and complications. Outcome Ten patients with a mean age of 72.6 years, a mean number of 8.5 pre-existing comorbidities and a mean ASA status of 3.1 met the inclusion criteria. The leading causes of defects, each with exposed tendons, bones, joint capsule, or joint, were chronic ulcers (n = 5) and soft tissue defects resulting from fractures (n = 3). In case of DMPB the success rate was 100% (no partial or total loss) with a short operating time (mean: 103 min) and a brief postoperative length of stay (mean: 11 d). In 2 patients (20%), DPBM surgery had to be discontinued intraoperatively and an alternative technique of defect reconstruction had to be adopted. The reasons included impaired muscle perfusion and fatty degeneration of the peroneus brevis muscle. Conclusion The DPBM flap allows straightforward, fast and safe defect reconstruction in the lower extremity, particularly in elderly, multimorbid and severely ill patients at risk. In patients with inadequate peroneal brevis muscle, however, DMPB surgery should be discontinued intraoperatively and the defect reconstructed using alternative techniques.