The current use of Personal Identification Number (PIN) for verification of the validity of a customer’s identity on Automated Teller Machine (ATM) systems is susceptible to unauthorized access and illegal withdrawal of cash from the ATM, hence, the need for more reliable means of carrying out user authentication. We present a three-tier authentication model with three layers of authentication using password, fingerprint and One-Time-Password (OTP). The identity of an ATM user is validated using password, fingerprint and OTP. Object-Oriented Analysis and Design Methodology (OOADM) was employed in the investigation of the existing system and analysis of the proposed system. Microsoft Visual Basic.NET and Microsoft SQL Server were employed in the implementation of the system. The result is a three-tier authentication model for ATM. Alphabetic keys and some special character keys were introduced to the existing numeric keypad for authentication. The ATM was interfaced with a fingerprint reader for improved security.