This paper evaluates the impact of the project Promoting Sustainable Agriculture in Borno (PROSAB) on the livelihoods of farming households in Borno State, Nigeria. Specifically, the paper identifies and provides information on farmers adoption of improved crop varieties introduced by PROSAB, measures their adoption rates and food security levels, and analyses the factors that affect the households food security status. The study used mainly primary data collected from a sample of 693 farming households in the study area. The analysis of data was carried out using descriptive statistics, Cost of Calorie calculations, and Logit regression techniques. The study results suggest that PROSAB has made a significant contribution towards improving the food security of households. In project intervention communities, food insecurity has been reduced from 58% in 2004 to 30% in 2015, indicating a 28% improvement in food security over the 11-year period. The paper clearly demonstrates how the adoption of crop technologies and crop management practices with linkages to markets has significantly contributed in improving households food security. The paper recommends increased promotion of improved crop technologies, trainings delivered to farmers on such technologies, and policies that enhance farmers access to inputs, credit, and output markets. Acknowledgement : The authors acknowledge the following; i) Canadian International Development Agency (CIDA) for funding the research (2004-2009); ii) financial assistance from the funded N2Africa project; iii) the contribution of IITA as an institution for providing a conducive environment and various Scientists from IITA that were involved in delivering research for development technologies and farmers training in the PROSAB project area, which had significantly increased crop yields, farmers income and enhanced household food security and iv) the contribution of Scientists from the University of Maiduguri and Borno State Agricultural Development Programmes who are Collaborators in implementing the PROSAB project.