Rock greenlings have a dark base color with reddish-orange spots across their entire body. These spots extend onto some of their fins. Like other greenlings, rock greenlings have an unusual projection on their forehead, referred to as a cirrus.
The rock greenling prefers living in rocky areas with fast-moving water, such as areas close to shore with heavy surge and rocky outcroppings. These habitat preferences make the rock greenling unavailable for commercial fishing as such areas are often hazardous for boats. Despite this, rock greenlings are often caught on line and reel as a game fish.