The KArlsruhe TRitium Neutrino (KATRIN) experiment, which is housed at the Karlsruhe Institute of Technology (KIT), is designed to measure the mass of the electron antineutrino in a direct and model-independent way with a sensitivity of 0.2 eV/c² at 90 % confidence level. This is achieved by a precise measurement of the beta spectrum of tritium. The electrons originate from a high luminosity windowless tritium source and are measured spectroscopically in an electro static filter (MAC-E filter). The topic of this work is the development, investigation and final integration of the Forward Beam Monitor (FBM) of KATRIN. The FBM is used in KATRIN to monitor the relative intensity of the electron flux, generated by the tritium source, with a precision of 0.1 %. Furthermore the FBM is able to record beta spectra with an energy resolution of σFWHM ≈ 2 keV for additional analysis. In order to achieve this degree of quality, the detector electronics, the detection device itself and its response to electron events must be well understood. Therefore measurements with electrons are performed as well as simulations which can reproduce the measured spectra. The detector can be moved to any position in the flux tube’s cross section with a positioning accuracy of 0.1 mm. The positioning is realized by a more than two meter long vacuum manipulator. High demands on the hardware are made since the setup must be suitable for the use in ultra high vacuum environment, it has to be non-magnetic and must fulfill all criteria for the use in a tritium bearing system. The present work presents the developing process from the prototype to the final commissioning of the FBM at KATRIN.