This study aimed to explore the role and mechanism of DYRK1a regulating ferroptosis of cardiomyocytes during myocardial ischemia-reperfusion injury (MIRI). H9c2 cells treated with oxygen-glucose deprivation/reoxygenation (OGD/R) were used as MIRI cell models and transfected with sh-DYRK1a or/and erastin. Cell viability, apoptosis, and DYRK1a mRNA/protein expression were measured accordingly. The levels of reactive oxygen species (ROS), iron, malondialdehyde (MDA), and glutathione (GSH) were determined. The expression of ferroptosis-related proteins (GPX4, SLC7A11, ACSL4, and TFR1) was detected using western blotting. The MIRI rat model was established to explore the possible role of DYRK1a suppression in cell injury and ferroptosis. OGD/R cells showed elevated mRNA and protein expression for DYRK1a. OGD/R cells transfected with sh-DYRK1a showed elevated cell viability, GSH content, increased GPX4 and SLC7A11 expression, suppressed iron content, MDA, ROS, ACSL4, and TFR1 expression, and reduced apoptosis rate, whereas co-transfection of sh-DYRK1a with erastin reversed the attenuation of sh-DYRK1a on MIRI. The suppressive effect of sh-DYRK1a on MI/R injury was confirmed in an MIRI rat model. DYRK1a mediates ferroptosis of cardiomyocytes to deteriorate MIRI progression.© 2023 The Authors. The Kaohsiung Journal of Medical Sciences published by John Wiley & Sons Australia, Ltd on behalf of Kaohsiung Medical University.