The Planetary Boundaries framework provides a holistic view of Earth's resilience by defining boundaries of a safe operating space for humanity and measurable control variables that describe the state of the Earth-system processes. Humanity is altering these processes, which has resulted in the transgression of several Planetary Boundaries. Researchers have downscaled the Planetary Boundaries framework onto smaller settings, yet its implementation on a company scale is rare and even more so when considering corporate sustainability reporting. In an attempt to assist ICT companies in identifying their negative impact on the Earth-system processes, this paper explores how the Planetary Boundaries framework can be integrated to complement current Information and Communication Technology (ICT) corporate sustainability indicators. The purpose is to define reportable company-scale proxy indicators (hereinafter 'proxies') based on the Planetary Boundary control variables, to assist companies in monitoring how impacts related to the Earth-system processes change over time. Based on data collected through an extensive literature review and interviews, sixteen reportable proxies are defined. The applicability of these proxies is also tested using one ICT company as a test case. The test case concludes that the current reporting practices of the studied ICT company are sufficient for two of the proxies but require minor or major refinements for the remaining ones. The deliverables of this study can assist in establishing corporate policies and aid companies to measure and follow up on the environmental impacts associated with the Planetary Boundaries framework over time. Moreover, this study does not address the downscaling of the safe operating space associated with the different boundaries, since defining such spaces for a specific company is not possible at this point. Therefore, applying the suggested proxies would not determine whether a company is operating within a fair and reasonable share of the safe operating space but rather indicate how its impacts develop over time.