The research of doped photonic glass has recently attracted much attention owning to the significant applications in various fields, including lasers, photovoltaics, and optical amplification. In this work, we present the design, fabrication, and experimental implementation of a novel fluorosilicate photonic glass-ceramics with broadband luminescence. We demonstrate that precipitated nanocrystals can be tuned by changing the heat-treatment temperature. This proposal offers an excellent opportunity for controlling the local environment around Ni2+ dopant. Consequently, the broadband and flat emission covering a waveband from 1200 to 2400 nm with a bandwidth of 605 nm can be realized. The possible physical mechanism, which can be attributed to the gradual change of nanocrystals from K2SiF6 to KCdF3 with the enhancement of the heat-treatment temperature, is also discussed.