Geminal diazides constitute a rare class of compounds where only a limited number of methods are available for their synthesis. We present the reaction of 1,3-dicarbonyl compounds (as exemplified by malonates, 3-oxoesters, and 1,3-diketones) with molecular iodine and sodium azide in aqueous DMSO providing a general access to geminal diazides. A broad range of geminal diazides with various structural motifs including sterically demanding substituents and ordinary functional groups were synthesized, and it was shown that the diazidation of 1,3-dicarbonyls can be selectively achieved even in the presence of other 1,3-dicarbonyls with substituents at 2-position. Additionally, several diazides were studied regarding their thermal stability.