This study assesses the effectiveness of green marketing strategies on the performance of fast-moving consumer goods (FMCG) firms in South-West Nigeria, focusing on green product design and green promotion. The objectives include examining the impact of green product design on product quality and analyzing how green promotion influences market penetration. A survey research design was adopted, with data collected through structured questionnaires from 595 respondents across five FMCG firms, selected from a population of 71,564 employees. Descriptive and inferential statistical tools, including regression and correlation analyses, were used at a 0.05 significance level. The findings show that green product design significantly affects product quality, explaining 30% of its variability (β=0.385; t=12.131; p=0.000). Additionally, green promotion demonstrates a strong positive relationship with market penetration (Pearson’s r = 0.617). The study concludes that the adoption of green marketing strategies, particularly in product design and promotion, positively influences FMCG performance in South-West Nigeria. It recommends that FMCG firms continue to prioritize sustainable practices to meet changing consumer preferences and enhance competitiveness.