The area of the purchase intention and purchase behaviour gap for consumers buying environmentally sustainable products with respect to the Theory of planned behaviour (TPB) framework has been studied extensively in past literature. But literature is scant when one studies the impact of ‘Actual behavioural control’ on the Purchase intention (PI) and purchase behaviour (PB) gap for the consumption of environmentally sustainable clothing. The TPB theory formulated by Ajzen in 1991 assumes that the actual behavioural control (ABC) will impact the purchase intention in the TPB. As there was no validated scale on the ABC in the past literature. Sheeran et al in 2003 made an attempt in testing the impact of Actual behavioural control on the purchase intention and formulate scale of Proxy measure of actual control (PMAC) in their study. Further Carrington et al. in 2010 tested the impact of the Actual behavioural control as a moderator in the purchase intention-behaviour gap qualitatively. The Empirical testing of the ABC to test the impact as a moderator in the Purchase intention-behaviour gap has never been done in the past studies. This study is the first study which analyses the impact of “Actual behavioural control” through a scale of “Proxy measure of actual behaviour” as a moderator in the PI-PB gap in the framework of the TPB for the consumption of sustainable clothing in India. Data collection has been done from Millennials of India. The research method of Structural equation modeling (SEM) has been used to assess the moderation impact of ABC on the purchase intention-behaviour gap. The findings of the study have shown that the PMAC positively moderates the relation of purchase intention and purchase behaviour for environmentally sustainable clothing. The outcome of the study is important to generate some crucial insights for the marketing strategies for the environmentally sustainable brands in Indian and to predict the behaviour of the Indian consumer towards such products.