The application of natural dyes is increasing each year due to their environmental friendliness and easy application on cellulose fibers. In this study, the natural dye from the Mexican marigold flower was extracted using a Soxhlet extraction apparatus. The extracted natural dye was applied on lyocell fabric with five different metallic salts using pre-mordanting and post-mordanting methods. It was observed that different color shade depth was achieved with different fixing agents. The color shade depth (K/S) washing fastness, light fastness, rubbing fastness, perspiration, and Fourier transform infrared (FTIR) test results of all dyed samples were excellent in both pre- and post-mordanting methods. There was no significant difference in the results between post- and pre-mordanting fi xation methods. However, the results showed that mordant ferrous sulfate had higher K/S value as compared to all other mordants. The dye extracted from marigold flower showed good dyeing efficiency with mordant to excellent colorfastness tests. FTIR results showed that there was no structural change in lyocell fabrics, before and after dyeing processes. Thus, a natural dye extracted from marigold flower has shown good colorfastness properties without damaging its fiber structure.