Despite government and other stakeholders efforts to promote improved cassava varieties (ICV) to farmers in Magharibi District in Zanzibar, cassava yield is yet below the Tanzania’s average of 8 t/ha and the average yield of 14 t/ha of Africa. Cassava Brown Streak Virus (CBSV) and Cassava Mosaic Virus (CMV) are the main causes of the yield losses; hence ICV were developed to address this issue, however, yet adoption of the ICVis poor. Farmers are still using local cassava varieties susceptible to pests and disease. This study is based on literature reviewed, interviews and collected data using semi structured questionnaireto determine factors influencing adoption of ICV in increasing farm yield. A cross sectional survey method was employed for the study. A total of 120 respondents were involved.In this study descriptive statistics tools and binary regression were employed to analyze the data using the Statistical Package for Social Science (SPSS). The study findingsindicated that smallholder farmers had negative attitude towards ICV.The major challenges observed were unavailability of inputs, scarcity of land and lack of training. Socio-economic factors such as age, household size, income, farm sizeand unreliable extension services significantly influenced the adoption of ICV. The study, therefore, concludes that poor adoption towards ICVhad reduced cassava production. The study recommended that the Government through the Ministry of Agriculture Natural Resources, Livestock and Fisheries should support training on the use of IVC. Again, further research needs to be conducted on the aspect of taste and maturity of Kizimbani (ICV), strengthen and motivate extension services as well as give support in terms of credit to smallholder farmers.