The fast‐moving consumer goods (FMCG) sector plays a crucial role in shaping consumer behaviour and supporting the sustainable development goals (SDGs), particularly in emerging markets like Ho Chi Minh City (HCMC), Vietnam. This study investigates the impact of green marketing activities such as green brand positioning (GBP), green product innovation (GPI), green distribution (GRD), green pricing (GRP) and green advertising (GRA) on consumer purchase intentions for green products in the FMCG sector. It also explores the moderating role of competitive intensity (COI) in these relationships. Data were collected from 340 consumers in HCMC, with 291 valid responses analysed using SmartPLS. The findings reveal a positive relationship between green marketing strategies and consumer purchase intentions. COI was not found to moderate the effects of GBP, GRA on consumer's purchase intentions for green products in HCMC. These insights highlight the importance of green marketing in promoting sustainable consumer behaviour, suggesting that FMCG companies in HCMC can enhance environmental sustainability by offering eco‐friendly products and aligning their marketing strategies with SDG 12 (Responsible Consumption and Production) and SDG 13 (Climate Action). This study contributes to the academic literature by addressing gaps in our understanding the interplay between green marketing and COI in emerging markets.