Kodiaks are naturally active during the day and only become nocturnal when faced with competition for food. They do not defend their territories and tend to have some of the smallest home ranges of any brown bear in North America. They are usually solitary but will often congregate in groups around large areas of plentiful food sources.

Bears are omnivores and will eat anything they find in the way of fish and plants. They will also dig for roots and tubers and even store leftover prey under moss. Kodiaks specifically enjoy fishing for salmon swimming upstream to spawn.

Kodiak bears reach maturity at around five years of age and have a mating season that lasts between May and June. They are seasonally monogamous and will only mate with one partner each season. Females usually bear anywhere from two to four cubs per litter and sometimes adopt cubs from other litters. Recorded life spans in the wild have been estimated at about 20 years.

Humans and habitat destruction are the two main threats for this large animal.

The Kodiak subspecies of the brown bear occupies the islands of the Kodiak Archipelago in southwestern Alaska.