Trebol has dark hair that is worn as a bowl-cut. He usually wears a small pair of sunglasses covering his small slanted eyes and has a broad flat nose, which is commonly seen with snot hanging out of it. He has a long, thick beard and some stubby hair on his upper lips. He also has a small scar just above his right eyebrow. He holds a golden scepter with a club suit design on the top with one red dot on each end. This scepter also has a lighter built into it which he can use to ignite his mucus.
His lips are a bit thicker than normal and his teeth are round and have some space between them. While he appears to be a large man due to his coat, in reality though he is a very skinny with a hunch and appears to be considerably taller than normal people. His attire consists of a long light blue coat made of mucus with a navy blue ring-pattern on it. He does not wear any footwear and is always shown with bare feet, but wears a mid-length chained-shackle on each of his ankles, which are not linked together. His coat made of mucus makes it look like he is wearing the coat. His posture and attire make him look like a giant snail.
As a child, Trebol lacked his mucus coat, but his nose was still constantly running. He wore a bowler hat and sunglasses, as well as a tattered shirt and pants. He used sandals before at some point ending up with shackles in place of actual shoes. He appeared to have grown up on the streets judging by his dirty, tattered appearance and having scrounged for food. At 18 and 33 years old, he lacked a beard. He continued wearing his bowler hat and also used a cane, which he may have replaced with the scepter he holds currently. At age 39, he was no longer using his bowler hat, taking on an appearance similar to his current one. He also changed the design of his mucus coat to represent his position as the Club seat of the Donquixote Family. When he was 47, Trebol had began using his gold scepter and changed his coat to a striped version. His hair took on a sloppy, dribbling appearance, oozing downward from the effects of his Devil Fruit, but Trebol later reverted back to the facial appearance he had during Doflamingo's takeover of Dressrosa.