Wildmutt appears to be a large orange dog-like creature with no eyes, ears, nose, or tail. He stands on all fours and his movements are somewhat apelike. His teeth are very defined and his bottom jaw sticks out of his mouth. The various spines found all across his body function similarly to whiskers with tactile sensing, and are not fur. Since Wildmutt has no eyes, he uses his sense of smell and hearing to navigate, which are aided by three gill-like nostrils located on each side of his neck.
In the Original Series, Wildmutt wore a black-and-white brace with the original Omnitrix symbol on his left shoulder.
In Ben 10: Omniverse, Wildmutt's lips have returned to being black and his forearms are a bit bigger. 16-year-old Wildmutt wears a green and white collar with the Omnitrix symbol.
