This research introduces an environmentally sound indigo-dyeing and cotton/polyester dyeing technology utilizing a high surface-to-volume ratio of nano cellulosic materials. Nanofibrilliated cellulose (NFC) is an engineered material composed of cellulosic fibers typically 10-50 nm in diameter and several micrometers long with a broad size distribution, resulting in about 1:50 average aspect ratio of the microfibrils. This dyeing technology involves coating cotton fibers with NFC loaded with dye molecules or particles, where NFC forms an entangled network of nanocellulose fibrils. This research study is divided into two parts. In the first study on natural indigo-based nanocellulose gel (NFC-NI) dyeing, cotton samples are coated with nanocellulose hydrogel (mixed with natural indigo particles) and post-treated with chitosan. Nanocellulose gel acts as a carrier for indigo particles, whereas chitosan is a physical crosslinking agent, improving the fixation and adhesion of nanocellulose gel with indigo particles. This method provides lighter or darker shades in a one-step process as opposed to the traditional method, where several dips are required in a reduced vat followed by oxidation to develop darker shades. This one-step technology secures over 90% dye fixation compared to 70-80% of conventional dyeing, comparable colorfastness properties, eliminates the use of reducing agents or alkali, and saves water up to a factor of 25. Moreover, the NFC-NI dyed fabric has antimicrobial properties which are safe for apparel and medical textiles without compromising comfort properties. In the second study, nanocellulose gel-based dyeing of cotton/polyester blend fabric provides one-step uniform coloration via the deposition of the colored (reactive dyes) nanocellulose fibrils on cotton fibers and sublimation of disperse dye into polyester fibers, followed by post-treatment with chitosan. Nanocellulose gel acts as an anti-migrating agent for disperse dye during sublimation in polyester fibers. In contrast, the reactive dyed nanocellulose is physically linked with the cotton fibers, coloring the whole fabric in a one-step process. Chitosan post-treatment improves color strength, fixation, and adhesion of dyed nanocellulose gel. NFC-based dyed cotton/polyester fabric achieved similar color performance, fastness properties, enhanced anti-wrinkle properties compared to the conventional dyeing method, and reduced water and auxiliaries usage up to factors of 18 and 20, respectively.