To activate your Citibank card without the physical card, log in to your Citibank online banking account or mobile app. Navigate to the "Card Services" section and select "Activate Card." Enter your card details as prompted, which may include the card number sent to you via email or SMS. Verify your identity through a one-time password (OTP) sent to your registered phone number or email. Follow the on-screen instructions to complete the activation process. If you encounter any issues, contact Citibank customer service for assistance. This process ensures you can activate your card quickly and securely without needing the physical card.