Remus was described as having a pale face with premature lines, and light brown hair that, as he progressed through his thirties, became more and more grey. The lines on his face and his greying hair were the results of the great deal of stress his body underwent with each full moon. His clothing is consistently shabby and patched, presumably because of his inability to find a decently-paid job due to his status as a werewolf.

In 1993, he sported a thin moustache, and from 1995 until his death, he sported more of a rough beard. He had scars cutting across his face and given Remus' comments on werewolf inflicted injuries being cursed wounds that are unlikely to fully heal after Fenrir Greyback's attack on Bill Weasley, it is possible he had more scars from his self-inflicted injuries during his transformations. In death, however, the flaws of his appearance were rectified, just like his friend Sirius Black; his spirit was described as "younger, less shabby, and his hair was thicker and darker."

He was also quite tall, standing six feet, two inches tall. His height was not often mentioned, but is notable as his height corresponded roughly to the full length of a wolf's body from nose to tail. His 162 pound weight also corresponded to his wolfish dimensions.

In his werewolf form, he was a large beast with grey fur, and the only differences between his appearance and that of a true wolf being his shorter snout, more human eyes, and tufted tail.