Nanosensors have been extensively evaluated and now widely adopted as a part of modern life as it has been seamlessly integrated into various devices that surround us. Nowadays, sensors are designed to identify specific cells at the molecular level for targeted drug delivery and monitor physiological processes within the body. The nanosensors measure various physical properties like concentration, electric, gravitational, magnetic forces, movement and speed, pressure, temperature, volume, etc. Moreover, wearable devices have also become very common in our society, they are largely dominated by physical sensors with only few sensors that work on optical and electrochemical mechanisms. This chapter highlights latest advancements in nanosensors for the detection of cancers, cardiovascular diseases, and pathogenic bacteria which are summarized. This chapter also provides a preliminary analysis about wearable nanosensors and their potential applications.