Using a content analysis approach, this study assessed the application of theories in Library and Information Science (LIS) research in Tanzania. The study’s specific objectives encompassed the analysis of the utilization patterns of theories in LIS research conducted in Tanzania, the identification of predominant theories, the highlighting of specific areas within LIS research where theories have been extensively applied, and the assessment of the level of integration of theories into research. While Kalervo and Vakkari’s classification scheme of LIS research areas was used to identify specific research areas where theories have been applied most, seven categories of theory talk were utilized to evaluate the degree to which these theories have been incorporated into LIS research. The study’s findings reveal a growing inclination towards the use of theories among LIS researchers, albeit at a slow pace. The study has also shown that TAM and UTAUT theories are the most frequently utilized, with information-seeking research being the primary area incorporating theories among all identified research areas. The findings also suggest that while a significant portion of the analyzed articles fall under the major category of the Continuum of Theory Talk, implying substantial incorporation of theories, a small number of them encountered difficulties in effectively integrating theories. The study, therefore, suggests that LIS educators should also prioritize the theoretical aspect of research in their curriculum. This will help researchers improve their understanding of the subject matter, leading to more reliable and precise research.