Abstract: The promising properties of photonic crystal fibers (PCFs) have sparked the interest of a number of research organizations. Due to the PCF’s air holes, liquid or gas samples can be inserted into them. This permits a well-controlled interaction between confined light and sensing samples, enabling the development of novel sensing applications. That was never conceivable with conventional optical fibers. PCF applications in sensing fields can be divided into physical sensors and biochemical sensors based on the parameter being measured. Physical sensors measure pressure, temperature, refractive index (RI), curvature, vibration, torsion, electric field, and displacement, among other physical characteristics. Biochemical sensors can detect chemical and biological (such as antibodies, cells, bacteria, enzymes, viruses, nucleic acids, etc.) substances. The measurement of the chemical RI is a crucial component of biochemical sensors. Due to their close relationship with biosensors, chemical sensors are commonly referred to as biochemical sensors. This article covers the detecting capabilities of surface plasmon resonance (SPR)-based PCF biochemical and physical sensors in addition to a variety of ways to enhance their sensing capacities.