Additive-based electroforming manufacturing methods for producing turbomachine components and other metallic articles are provided, as are metallic articles manufactured utilizing such manufacturing methods. In various embodiments, the method includes the step or process of additively manufacturing a sacrificial tooling structure having a component-defining surface region. A metallic body layer or shell is deposited over the component-defining surface region utilizing an electroforming process such that a geometry of the component-defining surface region is transferred to the body layer. The tooling structure is chemically dissolved, thermally decomposed, or otherwise removed, while the metallic body layer is left substantially intact. After tooling structure removal, the metallic body layer is further processed to complete fabrication of the metallic component. In certain implementations, the method may further include the step or process of depositing an electrically-conductive base coat over the component-defining surface region of the tooling structure for usage in the subsequently-performed electroforming process.