Abstract This study examined the relationship between service ambiance and customer patronage of supermarkets in Port Harcourt, Rivers State. Specifically, the study focused on two dimensions of service ambiance; store colour and store lighting. A correlational survey research design was adopted for the study. The population comprised thirty five supermarkets operating in Port Harcourt, while one hundred and forty copies of the questionnaire were distributed in the frame four copies each to supermarket managers, out of which one hundred and eleven valid responses were used for analysis. Data were collected using a structured questionnaire, validated through content and face validity, and reliability was established using Cronbach’s alpha with a coefficient of 0.98. The data were analyzed using descriptive statistics and Spearman Rank Order Correlation at a 0.05 level of significance. The findings revealed a strong and statistically significant positive relationship between store colour and customer patronage, as well as between store lighting and customer patronage. These results indicated that visual and atmospheric elements of the retail environment significantly influence customers’ emotional responses, satisfaction, and repeat patronage behaviour. The study concluded that service ambiance is a strategic marketing tool that shapes customer perceptions and loyalty beyond product and price considerations. It was therefore recommended that supermarket operators invest in well-coordinated colour schemes and appropriate lighting designs to enhance customer experience and sustain patronage in a competitive retail environment.