In optical sensing, the most recent important enabling technologies are based on either the longitudinal or transverse structuring of fibers. Microstructured fibers provide materials with dispersion characteristics unattainable with conventional materials, and enable otherwise unfeasible physical characteristics that can be tailored to specific sensing applications. This Spotlight presents a general overview on the integration of microstructured fibers, fiber micromachining, and functional coatings for optical sensing. Example applications include an optical fiber humidity sensor, sapphire fiber high-temperature sensor, PCF, and hydrogen sensor.