In the cytoplasm, actin and myosin together play important roles in cell migration, intracellular transport, regulation of cell shape, cell division, and endocytosis. These functions are carried out by myosin as a motor that moves along actin filaments and creates a motive force. Over the past 20 years, studies have revealed that actin and myosin also function in the nucleus and regulate various nuclear events, including transcription, gene positioning, DNA repair, and DNA replication. In this review, we summarize the known nuclear functions of actin and myosin and the associated molecular mechanisms. To date, studies on nuclear actin and myosin have been limited to animal cells. The possibility that the nuclear functions of actin and myosin are conserved in other organisms, particularly in plants, will be discussed.