The paper is on capacity building for sustainable digital information services in 21st century administration of academic libraries in Nigeria. Capacity building is termed as the building or the development of organization’s facilities, equipment, provisions, features, amenities, infrastructures and resources (human and physical) to foster growth and expansion. As such, capacity building needs to be introduced in the library which includes the professional building of human resources (professional library staff and other para-professional workers) and material resources. To achieve this goal, education and trainings on administration are given to the library staff for effective, efficient output and productivity. It can therefore be concluded that capacity building in academic libraries is very essential and crucial especially when considering the imperativeness of the services rendered by librarians for the general satisfaction of the intellectual quests of patron. The services must be rendered with ethics, principles and standard in order to maximize the output of the libraries. It can therefore be recommended that library staff should be trained and re-trained on administration for the benefit of delivering a well-rounded service in the library. Also, resources should also be provided for the both junior and senior library staff in academic libraries to sustain the network of policy fulfillment in the organization.