Magneto‐optic effect is attracting wide interest as it renders a contactless, potentially power‐free, highly sensitive and spatio‐temporal resolved way in both magnetic material characterization and light manipulation. Intensive explorations exhibit its potential in diverse applications such as optical communication, data storage, phase modulator, optical isolator, and magnetic‐field sensor. Noteworthy, atomically thin two‐dimensional (2D) materials represented by graphene demonstrate the interplay of large shape anisotropy as well as anisotropy in optical and magnetic properties, providing unlimited possibilities for the development of magneto‐optic effect and related applications. Here, we initiate the review with brief summary of the development history of magneto‐optic effect in parallel with the introduction of several typical 2D materials with unique magnetic properties. Thereafter, four important magneto‐optic effects of 2D materials are discussed, including Faraday effect, magneto‐optic Kerr effect, Zeeman effect and Cotton‐Mouton effect. Finally, we refine major challenges in further development of magneto‐optic effects and put forward prospects for several promising candidates of 2D magneto‐optic materials and related applications.