This study assessed the environmental knowledge, attitude and behaviour among market women in the Nigerian city of Ibadan, Oyo State. A quantitative research design was adopted and 403 market women were randomly selected from different markets in Ibadan. Questionnaire items adapted from Fah and Sirisena (2014) and Abdullahi and Tuna (2014) were pilot-tested among female artisans in Ibadan. Data collected from the study were analyzed using frequency counts, simple percentages, ANOVA, and regression analysis. Results of the analysis revealed that market women have good knowledge about erosion, water pollution, amongst others but lack knowledge in the area of soil degradation. Market women also have pro-environmental attitude based on their responses and they exhibit environmentally responsible behaviours in the area of tree planting, refuse disposal etc. but display irresponsible environmental behaviour by not switching off electricity gadgets when not in use. The findings also showed that there is a significant effect of environmental knowledge on environmental attitude, environmental attitude on environmental behaviour and the joint effects of environmental knowledge and attitude on environmental behaviour among market women.