Energy transfer-based biosensing is one of the most effective methods for fast and accurate biodetection. By designing appropriate energy transfer pairs as optical probes, a large diversity of analytes, ranging from small molecules to viruses, can be detected with high sensitivity and selectivity. Particularly, the development of optical nanoprobes has greatly improved the capability of energy transfer-based biosensing systems. By controlling the composition and structure of nanomaterials, both their optical characteristics and energy transfer pathways can be rationally manipulated, thereby enabling novel sensing processes. In this article, we focuse on various nanomaterials for composing energy transfer probes, and review recent advances of biodetection using optical nanoprobes in different biological settings.