A computer-implemented method for detecting malicious documents based on component-object reuse may include (1) identifying a plurality of malicious documents, (2) identifying a plurality of component objects that are contained within at least one malicious document from the plurality of malicious documents, (3) receiving an unknown document, (4) determining that at least one component object from the plurality of component objects was used to create the unknown document, and (5) performing a security action on the unknown document in response to determining that the component object was used to create the unknown document. Various other methods, systems, and computer-readable media are also disclosed.