The aim of the study was to determine Aliteracy as a threat to undergraduate students’ patronage of university library services in Sokoto state, Nigeria. Three research questions were formulated to guide the study. The researcher used a descriptive survey research design was used for the study. The population of the study comprises Three thousand (3000) Undergraduate students of the two universities, three hundred and forty-one (341) were sampled using a proportionate sampling technique. The questionnaire was titled (ATUSPQ). The instrument was face validated by three experts one from the Measurement and Evaluation unit and two experts from the department of Library and Information Science, University of Nigeria, Nsukka. Data collected were analyzed using percentage scores. The major finding of the study revealed causes of aliteracy: inappropriate guidance from the teachers, the invention of new technologies and social media, and mingling with illiterates. findings showed aliteracy led to low in-depth knowledge of various subject areas and impaired undergraduate intellectual abilities. It also revealed provision of relevant services, good human relations, and hybridization of library services are the strategies to increase the level of patronage to university library services. In conclusion, some recommendations were made which include: Libraries can also curtail aliteracy by providing staff and students with a full range of print and electronic resources to support teaching and learning and thereby enhancing students' patronage of library services. Librarians should do their best within their abilities to promote reading among the students by organizing literacy activities such as book discussion, library orientation, and library seminars, and the friendly demeanor of librarians will go a long way.