Mall Ninja is a braggadocious stereotype involving boasting about weapon proficiency and being "badass," despite a lack of mastery and respect for weapons practice. Obsessed with weapon tropes depicted in anime, action movies, or other violent fiction, the Mall Ninja is characterized by clumsy threats or posturing for superiority. Mall Ninja is an offshoot relation to the "Internet Tough Guy."

The main aesthetic concept of the Mall Ninja is that of being a poor mimicry of a fictional badass character. Their weapons, which they often carry in the eponymous malls, tend to be tacky and based on items that they have seen in anime. For example, they would have unnecessary ornamentation like colors, have no practical function, and are made of poor quality materials. Likewise, the clothing that they can typically be seen wearing is cheap, may fit poorly, and looks tacky. This is not based purposefully on camp, but rather being inexperienced in judging quality.

Most of the aesthetics and hobbies also overlap with Weeaboos . In fact, one of the main motivators of becoming a Mall Ninja could come from wanting to be like an anime character or because of the Dunning-Kreuger Effect which is defined as "a cognitive bias whereby people with low ability, expertise, or experience regarding a certain type of a task or area of knowledge tend to overestimate their ability or knowledge. Some researchers also include in their definition the opposite effect for high performers: their tendency to underestimate their skills." For example, a Weeaboo may mistake the hours of anime they watched as being hours of watching weapons training. These two groups, Weeaboos and Mall Ninjas, also share similar stereotypes such as a lack of hygiene, anti or asocial personality traits, "basement-dwelling", and an over-obsession with their hobbies.

As described by the Internet history site "Know Your Meme," the term was first documented being used around a thread on Glock Talk, a forum for gun owners, in 2001. Gecko45, a mall cop (sometimes derogatorily referred to as a "2.5" insinuating a mall cop is equal to half of one police officer which is a "5-0"), was paranoid about being shot on the job and talked about constantly wearing a bulletproof vest while having a firearm with him. The following is his defense of these habits which ironically, though unintentionally, became the very first Mall Ninja post. Linked here is an archived version of the original thread responsible for coining the term.

After this incident, the fact that Gecko45 worked in a mall and had claimed to be adept at skills held by real ninjas the term "Mall Ninja" became popular on the Glock Talk forum and spread to other internet communities as Mall Ninjas appeared on other social media sites such as Facebook and 4chan. In 2012, the subreddit r/mallninjashit was created for the purpose of posting images of Mall Ninja weapons, accessories, and memes. Later the same year, a page related to this cultural niche appeared on "Rational Wiki," a wiki-like site similar to this one with the purpose of documenting internet philosophy.