The bottom-up synthesis of nanostructures on surfaces relies on the self-assembly of nanoscale building blocks. However, the diversity of accessible nanostructures has been constrained by the limited choice of atomic and molecular building blocks that can be evaporated onto surfaces. Here, we overcome this limitation by utilizing complex inorganic ions generated through electrospray ionization as building blocks to synthesize nanostructures on surfaces. In this method, a high voltage is applied to the spray solution to generate a series of ions. With the help of a mass selection system, selected HMo_nS3_n+1^– and HW_nS3_n+1^– (n = 4–6) ions are deposited onto freestanding single-layer graphene. The Electrospray Ion Beam Deposition (ESIBD) growth technique used in this study yielded the formation of 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, as shown in Figure 1 and imaged by aberration-corrected Scanning Transmission Electron Microscopy (STEM). The two-component ESIBD experiments with MoS- and WS-ions resulted in nanoribbons with tuneable core-shell geometries, such as core-shell nanoribbons with a Mo-rich core and isolated W-rich shell, or a W-rich core and isolated Mo-rich shell. Concurrent MoS+WS deposition also produced nanoribbons with a uniform distribution of W-rich and Mo-rich areas, some of which were observed as MoWS alloy monolayers. This approach demonstrates the valuable potential to fabricate previously inaccessible nanomaterials on surfaces.