The rapidly growing adoption of Artificial Intelligence-enabled voice assistants across Indian markets creates a necessity to understand consumer behavioural patterns driving purchase intentions in e-commerce. Despite widespread usage, limited study exists on how motivational elements influence consumer trust and perceived usefulness of voice assistants in Indian online shopping. Drawing on the Motivated Consumer Innovativeness framework and Stimulus-Organism-Response model, this study examines how functional, hedonic, social, and cognitive motivations affect purchase intentions through trust and perceived usefulness as parallel mediators. Using purposive sampling, data were collected from 385 Amazon Alexa users in Telangana, India, via structured questionnaires employing 7-point Likert scales, and analysed using Partial Least Squares Structural Equation Modelling (PLS-SEM) with 10,000 bootstrap subsamples. Results indicate that functional motivators significantly enhance both perceived usefulness and trust, while social motivators increase usefulness and cognitive motivators strengthen trust. Notably, hedonic motivators do not significantly predict trust, and cognitive motivators demonstrate only a marginal association with usefulness. Both trust and perceived usefulness significantly mediate the relationship between consumer innovativeness and purchase intention, with trust exerting the strongest direct influence on purchase behaviour. The findings demonstrate that functional motivators outweigh hedonic and social influences in driving consumer adoption, suggesting that AI-enabled voice assistant services should prioritise practical utility, competence signalling, and reliability features over entertainment-oriented functionalities. These insights provide valuable guidance for e-commerce platforms and AI developers in designing user-centric voice assistant interfaces that enhance consumer trust and drive purchase behaviours in diverse Indian markets.