Starting an online casino business involves several key steps. First, conduct thorough market research to understand your target audience and competition. Next, secure the necessary licenses and comply with legal regulations in your jurisdiction. Choose a reliable software provider to ensure a seamless gaming experience, and develop a user-friendly website. Implement secure payment methods and robust security measures to protect user data. Finally, create a marketing strategy to attract players, utilizing social media, SEO, and promotions. With careful planning and execution, you can establish a successful online casino.