Kogoro is a private investigator, but he prefers to laze around all day. Kogoro can easily become infatuated with beautiful women and he would always boast of his career achievements so as to make them admire him. His dream woman is pop idol Yoko Okino, and he never misses her television show. Because of his behavior around attractive woman, he often embarrasses his daughter Ran Mouri and while it is not the reason why Kogoro's wife left him, it is why she hasn't come back.
While he is never outright called an alcoholic, Kogoro has a tendency to get intoxicated at social events, and Conan makes sarcastic remarks about him spending money on alcohol. In the anime, his office is littered with empty beer cans, and he keeps a well-stocked liquor shelf.
Throughout most of the series, he is seen as a pretty incompetent detective, often missing obvious clues and jumping to conclusions, though it should be noted that several of these conclusions were shared by other people on the scene, as well as the fact that Kogoro also follows many police procedures (asking questions, following leads) quite well. Despite his ineptness, he had been a prominent police officer under Inspector Megure ten years prior to the start of the series He is shown to have left the police force after events addressed in the second movie, Case Closed: The Fourteenth Target.
Thanks to Conan's undercover help in solving numerous cases, Kogoro's reputation as a detective grows quickly. He hardly remembers the solutions of any cases because of Conan knocking him out with tranquillizer darts so that he can announce the solution to the case using an imitation of Kogoro's voice as a proxy. However, Kogoro never seems to wonder about that and often boasts about his merits.
In later stories, there are times when Kogoro is actually able to solve crime cases without the help of Conan, especially when people he knows or cares about are involved. (It appears that, while he can connect the dots just fine, he can't actually find them as quickly as Conan does.) The most notable of these events takes place during a trip to a hot spring, where one of his old college friends is murdered. Kogoro is actually so disturbed and determined to find the killer on his own that Conan cannot bring himself to drug him, limiting himself to surreptitiously drawing attention to the necessary clues. Despite his frequent moronic analysis, Kogoro is actually smarter than most average men, as he is able to decipher certain clues and figure out things which most average men probably wouldn't figure out. He is even able to completely solve a crime himself in the ninth movie, Detective Conan: Strategy Above the Depths, and Conan applauds him mentally for it.
In college, Kogoro was the ace of the Judo team. However, he was highly vulnerable to stage fright. He is also an excellent marksman.
Kogoro's daughter, Ran Mouri, is also the daughter of Eri Kisaki, who is now living separately after an argument ten years prior. Despite constantly feigning disinterest in her, Kogoro still has feelings for his wife--he has even asked her to move back in with him, but she pretends not to hear him because she is not "ready" yet, though she still has feelings for him as well. These are expressed through jealousy when he comments on other girls' looks.