Context and discourse intonation have major influence on intended meaning in English-medium product advertisements on radio and television in Nigeria. Previous studies on Nigerian English phonology have confirmed the appropriate use of stress and intonation as the main challenge which many Nigerian speakers of English as a second language hardly manage to overcome. The studies have focused more on rule-based intonation (attitudinal and grammatical) to the neglect of context of use, which is essential to communication. This study, therefore, investigated the use of intonation in radio and television product advertisements in Nigeria in order to determine the primacy of social context in the representation of intonation meaning in advertisements. Using David Brazil's Discourse Intonation (DI) and some acoustic analysis for accurate pitch tracking, the study found out that the allocation of prominence to a word is an advertising model's decision based on context-of-use. There is a preponderant assignment of stress on structural words to achieve contextual prominence in the advertisement data. The proclaiming tones are dominant while the referring tones are few, and are used deliberately to attract the listener's attention. There is also the surprising sparse use of the rise-fall and fall-rise tones. Where allocated, the referring tone is used as a contextual common ground marker that sometimes needs reactivation. Intonation ambiguity is avoided in the selected advertisements by the prevalent use of the mid-key, which has the function of "additionally informing". No remarkable difference is observed between the contextual use of intonation in both radio and television advertisements.