Gem-aminofluorination of diazocarbonyl compounds has been achieved for the first time. This reaction proceeds under mild conditions and does not require any transition-metal promoter or catalyst. Treatment of diazoesters with N-fluorobenzenesulfonimide (NFSI), which serves as both a fluorine and nitrogen source, results in the facile construction of C-N and C-F bonds, providing aminofluorination products in moderate to excellent yields. Kinetic studies and DFT calculations have provided valuable insight into the potential mechanism for this novel N-F bond insertion.