Control of the chemical state and local environment of Cr dopant in glass through self-limited nanocrystallization is presented. Interesting wavelength-tunable and ultra-broadband near-infrared luminescence with the full width at half maximum of about 380 nm from obtained Cr-activated glass-ceramics are demonstrated. The results indicate that the presented method may be an effective means of fabricating multifunctional optical gain materials and wideband fiber light sources.