Reinforced concrete bridge decks deteriorate over time primarily due to increasing traffic loads, severe environmental conditions, especially in North America, and deferred maintenance. Condition monitoring of those structures in a timely manner is of a great importance for making informed decisions regarding maintenance, rehabilitation and replacement strategies to preserve their value, maintain their levels of service and safeguard against catastrophic failures. The objective of this paper is to introduce a comprehensive review of the current state of the art on condition monitoring of reinforced concrete bridge decks. Deterioration progression of bridge decks including different types of defects (i.e., cracks, corrosion, delamination, spalling, honeycomb and voids), their associated causes and effects are introduced. Commonly used non-invasive and non-destructive evaluation methods, including digital imaging, ground-penetrating radar, infrared thermography, half-cell potential, electrical resistivity, chain drag & hammer sounding, ultrasonic surface wave, ultrasonic pulse echo and impact echo, are presented with their capabilities and limitations. A bibliometric analysis was conducted to investigate the current trend in condition monitoring. The review also examines the frequency of methods used in condition monitoring and provide a classification of recent studies according to study type (e.g., field or laboratory experiment), joint use (i.e., whether study applied method as a stand-alone or hybridized it with another method) and performance (i.e., whether study investigated performance indicators of the applied methods or not). The key stages in monitoring condition states of bridge decks considering risks are discussed. Current practices, challenges and future perspectives are also highlighted.