Sustainability has now emerged as a critical priority for businesses. With consumers' increasing concern about the environment, many businesses are fast investigating and exploring new approaches, creating new ideas, and preparing different approaches to position their green brands in the minds of the customers as a solution for environmental problems. This study contributes to the literature by the being among the first to test the impact of green purchase intention on carbon emissions in Egypt. A new conceptual framework was formed by integrating three important theories: theory of planned behaviour (TPB), Cognition–affection–behavior theory of attitude (CAB) and Value Belief Norm (VBN) theory of environmentalism. The proposed model incorporates green brand positioning, consumer`s green attitude, perceived environmental knowledge, green behaviour, green brand knowledge, and green purchase intention as main factors. A questionnaire was designed, and we obtain 231 eligible responses. We used PLS – SEM method to test the validity and reliability of the measurement model and then testing the hypothesises using structural equation model. The finding revealed that higher consumer`s intention to purchase green brands (GPI) would lead to lower carbon emissions (CE) and thus improve the environmental quality. We found also a positive and significant effect of consumers' attitude (GA) towards green brands and green behaviour on consumers' intention to purchase green brands (GPI). On the other hand, green brand positioning (GBP), perceived environmental risks (PEK), and green brand knowledge (GBK) have insignificant impact on consumers' intention to purchase green brands in Egypt. Moreover, the results showed that perceived environmental knowledge (PEK) and green brand knowledge (GBK) have indirect effect on consumer's intention to purchase green products through their effect on consumers' attitude and thus CGA is said to play a significant intermediary role. Furthermore, GBK is said to mediate the relation between GBP and GPI.