This study aimed to evaluate the effects of four types of environmental enrichment on the improvement of companion dogs' behavioral problems due to separation anxiety. A total of 21 dogs of various breeds were included in the study. Data were collected to investigate the behaviors associated with anxiety in dogs, including vocalization, elimination, escape attempts, and destructiveness. A first stage, in which the dog and owner were together (P0), lasted 15 min, and a second stage, in which the dog and owner were separated (P1), lasted 15 min. After the dog and owner were separated (P1), the third stage (P2), during which the environment was enriched, lasted 20 min, and the fourth stage, following environment enrichment (P3), lasted 15 min. The results of the study indicated that compared to P0, the frequency of problematic behavior was highest during the 15 min following separation from the owner (P1). Following environmental enrichment, the average frequency of problematic behaviors in P2 decreased (P < 0.001) compared to P1. Environmental enrichment can also be used appropriately in the case of companion dogs, including shelter dogs or experimental dogs that use a limited kennel, and is a particularly effective means of improving the quality of life of dogs.