This chapter examines the use of Artificial Intelligence in onboarding and customer service. AI offers companies the opportunity to make the entire customer lifecycle more efficient and personalized. Initially, the AI-based personalization of the onboarding process for new customers is discussed, followed by the optimization of customer support and service through AI. In addition, AI-supported cross- and up-selling strategies as well as measures for customer retention and churn prevention are discussed. Finally, the analysis of customer satisfaction using AI is considered, supplemented by practical prompting tips for the use of ChatGPT and similar tools to further support these processes.