Metal additive manufacturing has revolutionized the manufacturing industry due to its capability of building complex parts without any part-specific tooling. Wire arc metal additive manufacturing is a process that uses the arc welding technique to build parts layer by layer. Robotic manipulators equipped with arc welding hardware can perform wire arc additive manufacturing and build complex geometries. In addition, the manipulator’s flexibility expands the capabilities of the additive manufacturing process. However, the geometries of the parts are limited by the flat substrate used for this process. This research aims to overcome this limitation by exploring a conformal substrate for wire arc additive manufacturing. Along with exploring the conformal substrate, this research will close the gap of the technical advancements and experimental validation required to build conformal metal parts. A conformal substrate makes the process planning complex. We address this complexity by making five novel contributions: (1) exploratory experiments with copper and iron as conformal substrate materials to determine if they are appropriate for the build material; (2) development of a corner accumulation detection algorithm for bead defect detection; (3) development of a process-specific tool-path planning algorithm to avoid molten metal from flowing under gravity; (4) development of a substrate placement planning algorithm to fit the trajectory in the manipulator’s workspace; (5) building and characterization of the built parts’ mechanical properties. Five truss-like parts are built using our process planning approach. Three of the truss-like parts are planar, and two truss-like parts are conformal. The parts are characterized to understand the effects of conformal substrate on the microstructure, microhardness, and T-peel strength.