Organic waste that accumulates and underutilized can cause environmental pollution. Among the organic wastes that can be utilized is avocado seed waste (Persea americana mill). Avocado seeds contain anthocyanins which have the potential to give red to purple colour so that they have the potential to be used as natural dyes for textiles. This study aims to determine the quality of colour strength, the quality of colour fastness to soap washing and the quality of colour fastness to sunlight. In this research, effect of mordant types (alum, lime and ferrous sulphate) to colour strength and colour fastness were investigated. The natural dye was hot extracted from avocado seed. Maintaining extraction and dyeing processes variables, the samples were then analysed using spectrophotometer to obtain the colour strength data. Gray scale was used to assess the colour difference due to colour fastness of washing and sunlight. Experiment results showed that ferrous sulphate generated the darkest colour of R% 88.07 with very dark criteria. Colour fastness to washing was not affected by mordant type thus provided the same value of moderate. Meanwhile, the best colour fastness to sunlight was given by system with ferrous sulphate mordant with good criteria.