We demonstrate a use of self-assembled monolayer (SAM) as a template to deposit in-situ Si nanoparticles fabricated by laser ablation. Scanning tunneling microscopy, atomic force microscopy observations, and photoluminescence measurements show that the Si nanoparticles deposited in situ on SAMs are round shaped, firmly attached to the surface, and remain stable for at least a couple of months. Control over the average size of the Si nanoparticles could be achieved, in the region where quantum confinement effect is important, by changing the Ar ambient pressure. Our results show that SAM endures the fierce heat, ions, and plasma generated during the laser ablation process, and the use of SAM could be extended as a substrate to deposit in-situ materials fabricated by laser ablation. In-situ deposition is important because it would facilitate fabrication of high functional nanoarchitectures based on this easily oxidized material. We believe that the wide range of available SAMs, different in chemical and electronic functionality, combined with the wide variety of nanostructures possible to fabricate by laser ablation, would open up a new opportunity to assemble these nanomaterials into high functional complexities of the next level.