Glass optical fibers doped with nanocrystals with optoelectronic function are highly anticipated for potential applications in optical communication, remote sensing, biomedicine, and nonlinear optics. In this review, a versatile fiber-drawing approach so called “melt-in-tube” (MIT) was represented to produce nanocrystals doped glass optical fibers. In the fiber-drawing process, the core is fully melted and the cladding is only just softened. Recent advances on the nanocrystals doped glass fibers including glass core-glass cladding fiber, crystal core-glass cladding fiber, and semiconductor core-glass cladding fiber were reported. In addition, the extensive applications of the nanocrystals doped glass fibers in the fields of fiber laser, fiber sensing, frequency conversion, photodetection and thermoelectric conversion were also discussed.