In this present world, a modern telecommunication infrastructural development is not only essential for domestic economic growth, but also a prerequisite for participation in the increasingly competitive world market and for attracting new investments. The main objective of the study is to examine the effect of promotional mix (advertising, sales promotion, public relations, personal selling, and direct marketing) on customer patronage among telecom subscribers in Lagos and Ogun States, Nigeria. Survey research design was used for the study. Data was collected through the use of questionnaire. Descriptive statistics was used to analyze the respondents’ biodata while multiple regression analysis was used to test the hypothesis formulated. Findings of the study revealed that advertising, sales promotion, public relations, personal selling, and direct marketing had significant effect on customers’ choice of mobile telecommunication network in Lagos and Ogun States, Nigeria. Advertising, sales promotion, public relations, personal selling, and direct marketing had significant effect on customers’ expense among telecom subscribers in Lagos and Ogun State. The study concluded that customer patronage will increase in mobile telecommunication firms when they provide adequate information about the services they offer through sufficient advertisements, publicity, personal selling, and direct marketing as well as provide the needed incentives that will encourage rapid purchase of their offers. The study recommended that telecommunication service providers should put in more efforts in their advertisement campaigns, carry out frequent sales promotion programs, build and maintain long lasting relationship with the members of the public, engage more in one-on-one interaction with prospective customers, and give room for customers to make enquiries, lodge their complaints, and offer suggestions on how they can be served better in order to attract more customers and increase their market share.