Sclerotinia sclerotiorum (Lib.) de Bary is a necrotrophic plant pathogen that causes cottony rot, watery soft rot, stem rot, white mold, and other disease symptoms in over 700 plant hosts around the world. Destruction of economically important crops, the lack of resistant cultivars, and the general challenge of controlling diseases caused by this broad-based pathogen call for continued research. However, in recent years, mass spectrometry-based proteomics analyses have been used to acquire a fundamental and in-depth molecular understanding of this fungal pathogen. In this review, we describe the characteristics of theSclerotinia sclerotiorum pathogen and examine its virulence factors, secreted proteins, and host suppression mechanisms. Furthermore, we review recent proteomics studies and extrapolate their primary findings for the identification and functional characterization ofSclerotinia sclerotiorum proteins. Finally, we discuss key findings that shape the understanding of the virulent factors and pathogenesis ofSclerotinia sclerotiorum and outline directions for future proteomic investigations of plant pathogens.