This study was designed to investigate market opportunity and sustainable development among SMEs in Nairobi County. A sample representation of 246 from three levels of management of all SMEs was taken from the study using simple random sampling. In the process of answering the basic questions, a questionnaire for this study consisted of two sections: the profile of the respondents and their business, and the main questionnaire, which contained questions on, Market opportunity. After the data, had been collected, it was analyzed for both parametric and non-parametric tests. Most of the data collected using the Likert scale was ordinal. Open-ended questions were analyzed using descriptive content analysis. There was error checking before data analysis to check for correctness of data input to the system cleared out transcription errors. Descriptive statistics such as the mean, the range, the standard deviation and variance gave a good idea of how the respondents reacted to the items of the questionnaire and how good the items measured were. Exploratory data analysis included reliability tests for constructs at both individual and composite level and measurement of both convergent and construct validity were carried out using regression analysis to determine the relationship between the market opportunity on sustainable development. The findings established the effect of market opportunity on sustainable development as having a good fit. The effect of market opportunity was indicated by regression model results (R2 0.526, P < 0.000). The independent variable, market opportunity had significant effects on sustainable development ((P > 003).