The Gemini High Resolution Optical Spectrograph (GHOST) is the next generation high resolution spectrograph for the Gemini South Observatory, and this has recently been commissioned in June 2022. In a single exposure, GHOST can obtain the full optical spectrum from blueward of 360nm to beyond 1 micron. Two modes of operation mean that either one object can be observed at R similar to 75000, or two objects can be observed at R similar to 50000. First light results have tested all aspects of the scientific performance of GHOST from the science user perspective, including a range of aquisition procedures and its two spectral resolution modes. On-sky observations of scientific and library targets suggest GHOST will be the most sensitive spectrograph across the full optical range of any of the 8-10m class spectrographs currently in operation. This paper presents a full discussion of the commissioning process, tests, on-sky performance and first science observations.