The coasts of West Antarctic Peninsula are strongly influenced by glacier meltwater discharge. The spatial structure and biogeochemical composition of inshore habitats is shaped by large quantities of terrigenous particulate material deposited in the vicinity of the coast, which impacts the pelagic and benthic ecosystems. We used a multitude of geochemical and environmental variables to identify the radius extension of meltwater impact of Fourcade Glacier into the fjord system of Potter Cove, King George Island. K-means cluster algorithm, canonical correspondence analysis, variance analysis and post-hoc Tukey's multiple comparison test were applied to define and cluster coastal meltwater habitats. A minimum of 10 clusters was needed to classify the 8 km2 study area into meltwater fjord habitats (MFH), fjord habitats and marine habitats. Strontium content in surface sediments is the main geochemical indicator for lithogenic creek discharge in Potter Cove. Furthermore, bathymetry, glacier distance and geomorphic positioning are the essential habitat explaining variables. Mean and maximum MFH extent amounted to 1 km and 2 km, respectively. Extrapolation of the identified meltwater impact ranges to King George Island coastlines which are presently ice-covered bays and fjord areas indicate an overall coverage of 200–400 km2 MFH, underpinning the importance to better understand the biology and biogeochemistry in terrestrial marine transition zones.