A controllable and area selective doping process, especially for p-type Molybdenum disulphide (MoS 2 ), is essential for the realization of various p/n junction-based devices. In this work, we demonstrate p-type doping of multilayer MoS 2 with phosphorus (P) as a dopant using a CMOS-compatible plasma immersion ion implantation (PIII) technique. Detailed physical characterization including XPS and SIMS, backed with ab-initio DFT calculations, confirms p-type doping in P-implanted MoS 2 that could be due to a combination of surface charge transfer from physisorbed phosphine ions and/or substitutional phosphorus present in the top few (~5) layers. Controlled reduction in current levels and positive V T shifts were observed in channel-doped MoS 2 transistors. Further, selectively doped gated p/n-junction diodes (rectification ~50X) have been demonstrated.