The study aims to identify flexible leadership's role in environmental sustainability through the mediating role of dynamic capabilities. The descriptive analytical approach was adopted by collecting data via a questionnaire and analyzing it to express the opinions of a sample of (204) managers in private pharmaceutical manufacturing companies in Iraq. Structural equation modeling (SEM) was used using (Amos 24.0) to test the hypotheses. The results indicate that flexible leadership positively affects dynamic capabilities and environmental sustainability, while dynamic capabilities also enhance ecological sustainability. Moreover, dynamic capabilities partially mediate the relationship between flexible leadership and environmental sustainability. The study also found out that companies implement flexible leadership as a means to achieve the desired results and act as a proactive facilitator and motivator, allowing organizations to improve most of their available resources and employ their dynamic capabilities to achieve proactive adaptation by sensing and seizing opportunities and reconfiguring, thus achieving the expected environmental sustainability goals and results.