Nanostructured materials, such as two-dimensional transition metal dichalcogenides and semiconductor quantum dots, possess unique functional properties. In this study, we utilized complex metal sulfide ions generated through electrospray ionization as building blocks to synthesize metal dichalcogenides on graphene surfaces. HMo_nS3_n+1^– and HW_nS_3n+1^– ions with n = 4–6 were deposited onto freestanding single-layer graphene using Electrospray Ion-Beam Deposition (ESIBD). The resulting nanostructures, as seen in Figure 1 and imaged by aberration-corrected Scanning Transmission Electron Microscopy (STEM), were anisotropic, single-layered, crystalline MoS2 and WS2 nanoflakes with sizes smaller than 100 nm² that self-assembled into MoS₂ and WS₂ nanoribbons extending up to 1 µm. The two-component ESIBD experiments with MoS- and WS-ions resulted in nanoribbons with tuneable core-shell geometries. For example, sequential MoS-then-WS deposition produced a core-shell nanoribbon with a Mo-rich core and an isolated W-rich shell, while sequential WS-then-MoS deposition resulted in core-shell nanoribbons with a W-rich core and an isolated Mo-rich shell. Concurrent MoS+WS deposition produced nanoribbons with a uniform distribution of W-rich and Mo-rich areas, with some areas observed as MoWS alloy monolayers. Through Density Functional Theory (DFT) simulations, we relaxed the structures of gas phase molecules and MoS₂ nanoflakes on graphene, which were consistent with the experimental results. This approach demonstrates the valuable potential to fabricate previously inaccessible nanomaterials on surfaces.