Despite the fact that the online criminal activities of Nigerian cyberfraudsters popularly known as the Yahoo-boys has attracted tremendous scholarly attention, little empirical information exists on their operational tools, techniques and underground networks. Hence, this study was motivated by the need to fill this observed gap. Social learning theory was adopted as theoretical guide while in-depth interview was principally deployed for data collection. Snowball sampling technique was utilized for the selection of 11 Yahoo-boys operating in Ibadan city. The results showed that Yahoo-boys who became wealthy through cyber fraud perpetration were being imitated by their peers who saw them as role models. Two major categories of operational tools were generally deployed by the Yahoo-boys for crime commission and illicit cash flows. Underground online forums, foreign criminal contacts and abroad-based criminal associates constituted the major sources of their operational tools and positively reinforced them towards cyber fraud. Yahoo-boys invested huge capital in the procurement of operational tools because they positively defined cyber fraud as a profitable business. There is the need for global law enforcement agencies and relevant international cybercrime-fighting institutions to constantly review and analyze the latest tools and techniques being employed by cyberfraudsters to effectively curtail their illegal activities.