This article is dedicated to building a single brand voice profile for social networks and messengers while maintaining identity when adapting to the platform format. A procedure is proposed that combines an unchanging verbal core with channel-dependent tone variations and automated compliance monitoring based on AI tools. The components of the voice profile are described, a comparison of channel characteristics is conducted, and a set of practices for developing guides, training teams, and controlling the quality of communications is compiled. The risks of inconsistent speech and audience cognitive dissonance are considered, and the task of ensuring recognition and trust in localization for language and culture is set. The methodological base includes the systematization of publications on SMM and integrated communications, as well as a comparative method for comparing the features of brand communication in social networks and messengers. Industry materials and research on emotional communication, opinion leaders, viral formats, and ML models for predicting popularity have been used to validate the solutions. Applied recommendations for embedding a unified tone in corporate regulations, work processes, and control tools are formulated. The article will be useful for brand strategists, marketers, SMM managers, customer service managers, corporate communications editors, chatbot developers, and digital media researchers focused on building a stable voice profile in a multi-channel environment.