Nature uses an array of remarkable protein motors and machines to facilitate life. However, the complex and highly evolved structures and mechanisms of these protein motors hinders the ability to answer the fundamental question of how to link chemical and mechanical action on the molecule scale. Attempts to address these issues using artificial motors made from small molecules and nucleic acids have been made. However, the production of artificial motors made of protein, the material selected by nature for the synthesis of molecular machines, has remained a challenge to the artificial motor and synthetic biology fields. Here we present the Tumbleweed (TW), an artificial protein motor that walks along a DNA track under external control. TW is built using a modular design approach, assembling three legs, each with a ligand-gated DNA-binding domain that enables selective interaction with specific sites along a DNA track. TW operates via a Brownian ratchet mechanism where steps are effected by diffusion and then rectified by controlling ligands. Using a combination of small angle X-ray scattering, mass photometry and surface plasmon resonance (SPR), we show that TW assembles correctly and interacts with DNA in a specific, stoichiometric and ligand-gated manner. Single-molecule Förster resonance energy transfer (smFRET) experiments demonstrate that TW steps along a DNA track in response to a defined sequence of ligand inputs. By creating TW using a modular approach, we show that motor function can emerge from an assembly of individual functional components. Our challenge now is to improve the performance of TW, as well as using components and lessons of TW in the design of increasingly more complex artificial protein motors.