This invention relates to a Denim protective fabric, with fire-retardant properties, and the process of dyeing the warp with indigo blue dye on a mixture of cellulosic and synthetic fibers, in order to obtain a permanently fire-retardant fabric, resistant to flame, heat, breaking, tearing, cutting and abrasion by impact. The resulting fabric is also antistatic and can be considered as a protective fabric like fire-retardant Denim and also a multi-risk fabric. The indigo blue dye is applied on a mixture of cellulosic and synthetic fibers with permanently fire-retardant properties such as fire-retardant viscose, fire-retardant modal, modacrylic, polyacrylate, polyamide, polyester, antistatic carbon, para-aramid, meta-aramid, polyamide-imide, polyethylene, PBI, with the aim of obtaining an authentic Denim jeans fabric, with the characteristics of the tincture based on indigo blue dye that loses its color on rubbing, with use and washing.