Plant cells are encased in a polysaccharide-based matrix referred to as the plant cell wall. This structure is of great importance to plant growth and development as it directs cell growth, regulates intercellular communication and water transport, and protects the cells against external stress. The cell walls are largely built of polysaccharides, most of which are synthesized in the Golgi and secreted to the apoplast. However, cellulose, which is a principal component of the cell wall and the most prevalent biopolymer on Earth, is synthesized at the plasma membrane by Cellulose Synthase (CesA) complexes. While we are beginning to understand how the CesAs are controlled at the plasma membrane we do not understand much about how they are trafficked to and from the membrane, and how this process is regulated. We have identified a new endocytic adaptor-related complex in plant cells and we show that this complex is the major driver for internalization of the CesA complexes from the plasma membrane. Our research provides new avenues for how to modulate the cellulose content of plants and might therefore be of direct relevance to the agricultural sector.