Abstract Background Immune dysfunction and inflammation participate in the pathophysiology of bipolar disorder (BD). Abnormal levels of inflammatory markers, namely, red cell distribution width (RDW) and platelet distribution width (PDW), were detected in BD. Electroconvulsive therapy (ECT) for various mental disorders including BD was linked to changes in these inflammatory mediators. Hence, we aimed to assess the impact of ECT on PDW and RDW in patients with BD. Methods Seventy-two patients aged ≥ 16 were enrolled in the current prospective cohort study over 6 months, diagnosed as BD based on DSM-IV and indicated for ECT and complete blood count (CBC) drawn pre-ECT and after four ECT sessions. Results By the end of the ECT sessions, we noticed a significant elevation in PDW with lowering in RDW levels. However, no significant differences were detected before and after ECT regarding platelet (PLTs) count, mean platelet volume (MPV), and Plateletcrit (PCT). Conclusion ECT seems to improve the CBC-derived inflammatory markers (RDW and PDW) subsequently, improving the underlying inflammatory process in BD without disturbing PLT homeostasis which support its anti-inflammatory role in BD.