The use of natural dyes for textiles has attained attention due to their ecology, minimum impact on the environment and pollution. Therefore the objective of this study is to dye Lyocell fabric with natural dye extracted from orange peel for comparative analysis of colour efficiencies (K/S), CIE L*a*b* values and the colour fastness properties. The mordants applied were ferrous (II) sulphate and copper (II) sulphate. For the extraction of the dye, the aqueous extraction method was used. The pre-mordanting method was used and the dyeing effect on Lyocell fabric was analyzed at concentrations of 2% and 4%. It was observed that the mordant type employed had an influence on the colour efficiency and the colour coordinates of fabric dyed with Citrus aurantium dye. The colour efficiency (K/S: 4) and colour fastness to washing, light, rubbing and perspiration in all the dyed samples were better and excellent (grade 4–5) at 4% concentration. In overall results, the pre-mordanting method at 4% concentration gives the best results of colour efficiency and colour fastness properties. The performance analysis of colour fastness was also statistically significant at the 0.05 level.