Silicon (Si) has widely been used as an essential material in the modern semiconductor industry. Recently, new attempts have been actively made to apply Si to a variety of fields such as flexible electronic devices and biosensors by manufacturing Si nanomembranes (NMs) having nanometer thickness. In particular, as the thickness of Si is reduced to a nanometer scale, its mechanical, electrical, and optical properties differ from that of its bulk form, which provides opportunities for the development of new conceptual devices. In this review, we present recent advances in Si NM technology that exhibit functional features different from the bulk materials. In addition, we discuss the opportunities and current challenges related to this field.