This dissertation investigates the moderating effects of market orientation application on performance among SMEs in Nigeria. It examines the most pertinent factors and dimensions emerging from a review of previous related work. This provides a base for the study to examine the dimensions and antecedents of market orientation, the effects on SMEs operations, and importantly, on market offerings and customer satisfaction under the government economic/market reforms in the economy. Market orientation focuses on, and entrenches the use of market intelligence and information to determine market offerings to meet customer satisfaction. MARKOR scale, the dominant methodology for measuring market orientation, emphasises application of intelligence generation, intelligence dissemination and responsiveness among firms to meet and improve customer satisfaction in operations. The research is important in that it provides an holistic overview of MARKOR scale application by examining the implication and effects of the dimensions in the light of SMEs operations in a developing economy like Nigeria. Importantly, the study examines market orientation implementation with reference to ongoing economic and market reforms in the economy. The underlying research approach used was quantitative technique. This was employed to give adequate interpretation and meaning to the causal relationships that exist among variables as they interacted in the operations and decision processes. This resulted in development and testing of hypotheses and application of relevant statistical instruments that are appropriate for the study. The hypotheses were related to the dimensions of market orientation and other themes that the study covered. The use of SPSS 10.1 was employed for data analysis, and application of Cronbach alpha for reliability and internal consistency of data. A total sample of 234 respondents was drawn from specific states across the six geo-political zones of the economy. The statutory definition of SMEs guided the sampling process. As a part of method/data triangulation procedure, the qualitative technique was also employed to give adequate information and meaning to analysis and finding. The main finding of the research was a mixture of confirmation of existing findings on market orientation application in businesses, and new developments in relation to the operation of SMEs in Nigerian economy. The new developments were found in terms of the effects on performance (financial and non-financial categories), responsiveness and managerial representation, internal management, reward systems and effects under economic reforms. For example, the cross-functional and multi functional of staff to strengthen market oriented behaviours, and higher consumer representation or information among SMEs. By and large, the study shows the applicability of market orientation and the usage of MARKOR scale among SMEs in Nigerian economy; hence, they provide a basis to understand developments in the market and areas of improvement to enrich customer satisfaction.