This paper addresses the development of a modular hardware architecture for the design/ construction/operation of a remotely operated vehicle (ROV), based on systems engineering. The Vee model is first presented as a sequential process that emphasizes the validation processes with stakeholders and verification plans in the development and production stages of the ROV’s life cycle. The conceptual design process starts with the mapping of user requirements to engineering specifications, using the House of Quality (HoQ), a quality function deployment tool that allows executing a functional-division-based hardware design process that facilitates the integration of components and subsystems, as desired for modular architectures. Then, the functional division and hardware architectures are described, and their connection is made through the proposed system architecture that sets the foundation for the definition of a physical architecture, as it involves flows that connect abstract functions with a real context. Development and production stages are exemplified through the design, construction, and integration of some hardware components needed for the remotely operated vehicle Pionero500, and the operational stage briefly describes the first sea trials conducted for the ROV. Systems engineering has shown to be a very useful tool for the development of marine vehicles and marine engineering projects that require modular architectures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.