The study population comprised of personnel of university law libraries in all accredited nineteen universities offering law at undergraduate level in South-west, Nigeria. Using Media Richness Theory as theoretical framework, descriptive survey design of correlational type was adopted for the study. Out of the 107 copies of the questionnaire administered, 97 were validly completed, returned and used for the analysis. The findings from the study revealed positive significant relationships between use of mobile applications for promotion of law library services and age of respondents and years of work experience. Meanwhile, there were no significant relationship between use of mobile applications for promotion of law library services and library policy, ICT skills, adequacy of funding, environmental factors and infrastructure. It also shows the joint contribution of personal factors (gender, age, status, position, academic qualification, years of work experience and section of the library) on the use of mobile applications for promotion of law library services in South-West, Nigeria. The study shows that personal factors particularly influence the use of mobile application for the promotion of law library services. It is recommended that there is awareness and capacity building among staff of law libraries on the use of mobile applications in promoting law library services. Keywords: Personal factors, Organisational factors, Mobile applications, Promotional services, University, law libraries in South-west