The term watchdog journalism is strongly related to the practice of investigative journalism. A watchdog is defined as "a person or group of persons that acts as a protector or guardian against inefficiency, illegal practices, etc." by the Collins English Dictionary. In news journalism, a watchdog journalist also fulfills this function of being a guardian. To perform in an investigative manner, the journalist is in the "role" of a watchdog. Watchdog journalism cannot be defined by the amount of investigation alone, however, but is used in many different contexts. It also is stated "contingent on the existing social, political, and economic conditions and a reflection as much of the historical moment as it is of pre‐existing structures and media cultures". Watchdog journalism can be located in a variety of news media, such as radio, television, Internet, and print media where it may be seen as "a unique strength of newspapers", and additional new media and concepts such as weblogs and citizen journalism. Watchdog journalists also are called "watchmen", "agents of social control", or "moral guardians".

Another term in this context is the "detached watchdog". The concept of the detached watchdog emerged from an extensive study on journalism cultures conducted by communication researcher Hanitzsch and others. The detached watchdog is described as "dedicated to objectivity, neutrality, fairness, and impartiality".

he role of a watchdog journalist can be that of a protector or guardian. The role of a watchdog journalist as a guardian is to supply the citizens with information they must have "to prevent the abuse of power", and to "warn citizens about those that are doing them harm". In order to conduct their role as a watchdog, journalists need to have a certain distance from the powers and challenge them, as opposed to "propagandist" journalists, who are loyal to the ruling powers and elites. Because of the power distance and its overseeing function, watchdog journalism often officiates as the fourth estate, or is used in the context of that term. The array of topics for watchdog journalism is wide and includes "personal scandals, financial wrongdoing, political corruption, enrichment in public office, and other types of wrongdoing". In order to expose wrongdoings the watchdog aims at "finding hidden evidence". The aforementioned aspects are necessary for the role of the watchdog journalist to help "maintain order" and "warn against disorder".