The broad objective of this study was to conduct an ex ante economic impact of maruca Bt cowpea in Kaduna and Sokoto states, Nigeria. The specific objectives of the study were to examine consumers‟ awareness/perceptions and preferences regarding Bt cowpea, to determine how much consumers were willing to pay for Bt cowpea quality attributes, to determine the effect of socio-economic characteristics of consumers on willingness to pay for the Bt cowpea, to predict the potential market share of transgenic Bt cowpea, and to measure the aggregate welfare net benefit of introducing the new Bt cowpea in the marketplace of the study areas. Using multi-stage random sampling technique, 12 Local Government Areas, 12 urban and 12 rural markets were randomly sampled from six Agricultural Development Project (ADP) Zones, in Kaduna and Sokoto states, Nigeria. A random sample of 208 consumers was selected from the cowpea consumer population. Data collected were analyzed using descriptive statistics, conditional and mixed logit discrete choice models. The descriptive combined result show that 19.71% of the respondents said they were aware of the new Bt cowpea, implying that consumer awareness of Bt cowpea was low in the study area. The result further revealed that about 20.19% respondents had little perceived knowledge of Bt cowpea in the study area. The results also indicated that 6.25% of the respondents exhibited ethical concerns while 2.2% perceived risks of toxic, 19.23% perceived that Bt cowpea has no disadvantages and 8.17% perceived the risks of environment in the study area. The conditional logit pooled results revealed that the respondents preferred cowpea large grain size and placed a relatively high level of importance on safety attribute of Bt cowpea in the study area. Results further showed that consumers were willing to pay premium or higher prices on cowpea large grain size (N92.90) and safety attributes (N186.77) in the study area. The age of consumers had a positive sign (0.002) and significant effect on willingness to pay for cowpea attributes at 5% level in the study area. Furthermore, the results of predicted market share indicated that the potential market share of Bt cowpea was low (40%) compared to conventional cowpea (60%) in the study area. Results from welfare analysis indicated that consumers would experience positive welfare net benefit of N242 billion in urban and N395 billion per year in rural areas, respectively, in the study area. This implies that Bt cowpea commercialization would have a significant impact on consumers‟ welfare in both rural and urban areas at 1% and 5% levels, respectively. The mixed logit pooled results revealed that the price coefficient showed the expected negative sign (-0.08) and was statistically significant at 5% level and distributed log normal. The coefficient of cowpea large grain size was normally distributed with an estimated mean of 0.742 and estimated standard deviation of 1.457. In other words, two third of the consumers had positive preference while one third had negative preference for cowpea large grain size. It was concluded that the mixed logit provided better representation of consumers‟ preferences or choice situation and give more information than conditional logit model. The study recommended the need for policy on decision-making to incorporate a few regulatory steps on safety into the regulatory approval and to assess the safety of Bt cowpea to be introduced. It is also recommended that research should ensure that insert resistant is not broken down.