Purpose <p>In this work, a life cycle assessment (LCA) was conducted to compare the environmental impacts of a microbial fuel cell (MFC) using a biotic cathode based on graphite/<i>Chlorella vulgaris</i> microalgae against using a conventional abiotic platinised titanium (Pt-Ti) or graphite cathode.</p> Methods <p>Electrode production, microalgae production, and MFC operation were key parameters of interest in the LCA. Indices adopted for comparing environmental burdens include global warming potential (GWP), acidification potential (AP), and eutrophication potential (EP), among others.</p> Results and discussion <p>Abiotic graphite cathode in a microbial fuel cell exhibited the lowest environmental burden. Replacing the titanium with graphite in the abiotic platinised titanium cathode reduced GWP by 99%. The microbial fuel cell operation itself had an insignificant contribution to the environmental burden. However, the microalgae cultivation and harvesting unit operations had negative environmental indices. AP and EP of the Pt-Ti and abiotic graphite scenarios are generally low (ca. 10⁻⁵ units) and insignificant. The fertiliser added during microalgae cultivation contributed significantly to AP and EP. Using wastewater to cultivate the <i>Chlorella vulgaris</i> reduced, but did not eliminate, the overall environmental burden compared to using fertiliser.</p> Conclusion <p>The results suggest that using pre-cultivated microalgae in the cathode of an MFC does not further reduce the overall environmental burden compared with using a conventional graphite-aerated cathode electrode unless cultivation emissions are assigned to a dual wastewater treatment process. As such, the environmental benefits of using microalgae in MFC operation are only realised if microalgae are cultivated for wastewater remediation.</p>