The importance of session management security lies in safeguarding user sessions and protecting sensitive user data. Managing sessions securely prevents unauthorized access, maintains confidentiality, integrity, and availability of data, and protects user privacy. Implementing secure cookies, setting session timeouts, and ensuring proper logout functionality are crucial to managing sessions securely. Additionally, using server-side session management and validating logouts can further enhance security. By following these best practices, developers can help users feel confident that their credentials and confidential information are safe.