Ecological memory refers to the influence of past events on an ecosystem’s response to external or endogenous changes. Whereas memory’s contribution to ecosystem dynamics is well recognized, its role in microbial community dynamics has gained limited attention. Quantitative models of microbial communities have recently shown how resilience and multistability can emerge from interactions between community members under environmental perturbations. Here, we propose a general approach to incorporate memory into dynamical ecological models, and apply it to a topical microbial community model to demonstrate how memory: (1) slows down the overall dynamics, thus enhancing resistance while reducing resilience to perturbations; (2) can prevent state shifts and mitigate hysteresis, thus increasing resilience; (3) favours long transient dynamics, such as long-standing oscillations and delayed regime shifts; and (4) contributes to the emergence and persistence of alternative stable states. These results highlight the fundamental role of memory in key aspects of microbial community dynamics.