This study was conducted with an aim to develop a novel washing-off method to remove unfixed reactive dyes from cotton fabrics with lesser amount of water and energy, without compromising color fastness properties. In this context, ozone was utilized very first time in washing-off process to ascertain color fastness properties of selected reactive dyes. After deep shade dyeing (6% owf) of C.I. Reactive Black 5, C.I. Reactive Blue 19, and C.I. Reactive Orange 7, dyed fabrics were subjected to both conventional and new washing-off methods. The new washing-off process was carried out by introducing the ozone at the bottom of bubble column reactor containing the fabric and washing-off liquor. The new process took place at room temperature using a single bath without draining or refilling with fresh water. Fabrics washed-off with both methods were compared in terms of washing fastness, crocking fastness, change of color, and magnitude of total color difference ( ∆E*cmc (2:1) ). The color fastnesses properties and final shade of the ozone treated fabrics were found to be comparable to those washed-off conventionally. Key Terms: Washing-off, Reactive dyes, AOP, Ozone, Bubble column reactor, Fastness