The disclosed computer-implemented method for customizing security alert reports may include (i) identifying a local machine learning model that predicts how a client responds to security alerts generated for the client, (ii) identifying a set of peer machine learning models that predict how a set of peers of the client each responds to security alerts generated for each respective peer, (iii) measuring a level of similarity between the client and each respective peer of the set of peers according to a similarity metric to create a similarity model, (iv) aggregating the local machine learning model and at least one of the set of peer machine learning models based on the similarity model to create an aggregated machine learning model, and (v) protecting the client by applying the aggregated machine learning model to customize an electronically displayed security alert report. Various other methods, systems, and computer-readable media are also disclosed.