Surgical orbital decompression is achieved by expanding the volume within the bony orbital cavity or removing orbital fat. It is done to reduce proptosis, relieve optic nerve compression, alleviate symptoms of orbital pressure and improve cosmesis. Since first described in 1911, techniques have evolved to achieve effective decompression of orbital walls with reduced surgical morbidity. Decompression surgery can be performed via open, transcaruncular and endoscopic approaches, and there has been a move towards minimally invasive options. The approach used should be tailored to individual patients’ needs in response to their disease phenotype, clinical and radiologic assessment and personal requirements. Careful pre-operative planning is key to success, and potential risks of the chosen surgery should be discussed with patients prior to proceeding. Decompression is effective in achieving up to 7.5 mm of proptosis reduction in published series, but results can regress and proptosis partially recur in a minority of cases due to factors including recurrent active disease and reformation of medial wall periosteum.