The purpose of this study is to evaluate the effectiveness of the existing Government communications strategies and their support on the uptake of routine immunization services by mothers in urban informal settlements. Studies that have been done on promoting the number of Fully Immunized Children (FIC) in Kenya are only mainly on the area of public health and its policies. This study therefore seeks to advance knowledge because there are no appropriate communication strategies by the Ministry of health on routine immunization at the community levels as in the case of Kangemi slum. Readily available reference material on the effectiveness of communication strategies or even a communications plan and ensuring FIC in urban informal settlements is also lacking. This study was done in Kangemi, one of Nairobi’s slums. Nairobi is the capital and largest county and city in Kenya. A majority of Kenyans who live in urban areas are poor. A descriptive survey of mothers with children under two years (12-23months) of age was carried out. A simple random sampling technique was used at the study sites and the data was collected via administered interviews, focus group discussions and document analysis. The major finding of this study is that interpersonal communication seems to be the most preferred method of communication by mothers in urban informal settlements and that the Ministry of Health through the Division of Vaccines and immunization has not done enough sensitization to create awareness and knowledge of the existing vaccines in the Kenya Expanded Program on Immunization schedule As per the SDG’s and the Kenya Vision 2030, this study is important in reducing child morbidity caused by vaccine preventable diseases. Checking the effectiveness of communication strategies that influence full child immunization in a sample of the urban poor in the country and picking up effective strategies that apply in such areas such as interpersonal communication; will enable the government to come up with new, effective and well-tailored communication strategies as well as well-articulated policies, projects and programs towards immunization especially in ensuring the healthy growth of children in these underprivileged settlements and enhance their quality of life.