The paper presents SMARTmBOT, an affordable, open-source mobile robot platform designed for extensive robotics research and education, built on ROS2 and featuring a low-cost, modular, customizable, and expandable design. With most components 3D-printable and a total cost of about $210, SMARTmBOT is accessible and easy to repair, equipped with a comprehensive sensor suite suitable for various tasks like navigation and obstacle avoidance. Its capabilities are demonstrated through diverse experiments, and all source code for sensor integration, camera streaming, and robot control is available in the GitHub Repository.