Currently, voice assistance as a user interface through mobile applications is being developed for intelligence systems, especially for smart homes, which allow users to remotely control their home appliances. This article presents a study of acceptance and adoption of using the Internet of Things (IoT) in the form of mobile applications that use voice assistance for commanding the switch to turn on and off an appliance in a smart home. The objectives are to study the factors and the relationship between the factors that influence the adoption of the use of mobile application-based voice assistance for smart homes. The framework is constructed in the form of a unified theory of acceptance and use of technology (UTAUT). Confirmatory factor analysis (CFA) and structural equation model (SEM) are used to test the goodness of fit of the model and hypotheses verification. According to the data analysis findings, performance expectancy, effort expectancy, and social influence positively influence the behavioral intention, and facilitating conditions positively influence the use behavior of using voice assistance for smart homes. The analysis of mediators reveals that age, experience, and voluntariness of use influence behavioral intention, whereas gender does not influence behavior intentional to use voice assistance in a smart home.