Background <p>Pursed-lip breathing (PLB) is common in chronic obstructive pulmonary disease (COPD) as both a compensatory pattern and a rehabilitation technique, yet the biomechanical properties of the orbicularis oris and buccinator muscles remain underexplored.</p> Aims <p>The aim of this study was to compare the tone and viscoelastic properties of the orbicularis oris and buccinator muscles among COPD patients with PLB, COPD patients without PLB, and healthy controls, and to examine the relationship of these parameters with pulmonary function.</p> Subjects and methods <p>This prospective observational study included 67 participants: COPD with PLB (<i>n</i> = 21), COPD without PLB (<i>n</i> = 22), and healthy controls (<i>n</i> = 24). Inclusion criteria were age 40–65&#xa0;years, body mass index 18.5–29.9&#xa0;kg/m², and clinically stable COPD (GOLD stage 1–3). Muscle biomechanics were assessed using the Myoton®PRO device, and pulmonary function was evaluated by spirometry in accordance with ATS/ERS standards.</p> Results <p>In the COPD group with PLB, FVC, FEV₁, and FEV₁/FVC values were significantly lower compared to the non-PLB group (<i>p</i> &lt; 0.05). Both COPD groups demonstrated higher tone and stiffness but lower elasticity in the orbicularis oris and buccinator muscles compared with healthy controls (<i>p</i> &lt; 0.05). No significant differences were observed between COPD subgroups. In the PLB group, orbicularis oris elasticity showed a negative correlation with FVC (<i>r</i> = − 0.547) and FEV₁ (<i>r</i> = − 0.614).</p> Conclusion <p>In COPD, PLB is both a compensatory pattern and a marker of disease severity. Reduced orbicularis oris elasticity relates to impaired lung function, and facial muscle biomechanics may serve as a non-invasive biomarker, supporting the inclusion of orofacial muscles in rehabilitation.</p>