Since their inception in the 1970's, the GOES satellites have monitored Earth's highly variable magnetic field using magnetometers. The GOES-R magnetometer requirements are similar to the tri-axial fluxgates that have previously flown. GOES-R requires measurements of three components of the geomagnetic field with a resolution of least 0.016 nT and sampling at a 2 Hz threshold with goal of 8 Hz. This instrument will provide measurements of the space environment magnetic field that controls charged particle dynamics in the outer region of the magnetosphere. These particles can be dangerous to spacecraft and human spaceflight. The geomagnetic field measurements are important for providing alerts and warnings to many customers, including satellite operators and the power utilities. GOES magnetometer data are also important in research, being among the most widely used spacecraft data by the national and international research community. The GOES-R magnetometer products will be an integral part of the NOAA space weather operations providing, for example, information on the general level of geomagnetic activity and permitting detection of magnetopause crossings and storm sudden commencements. In addition measurements will be used to validate large-scale space environment models that are used in operations. In this presentation, in addition to briefly describing the instrument requirements and its uses, we will also describe some of the products under development through the Algorithm Working Group activities.