Companies all over the world invest substantially on advertisement yearly. This is because advertisement has been adjudged as a major promotional tool capable of influencing consumer buying behaviour. However, some companies are still in doubt on the ability of advertisement to favourably influence consumers’ buying attitude. Therefore, this study investigated the influence of advertisement on consumers’ buying behaviour of Smartphones in Ibadan metropolis, Nigeria. Two research questions and three hypotheses were formulated and tested in the study. A survey research design was employed for this study. The population and sample consisted of the Four hundred and four (404) Smartphone retailers in all the four hundred and four (404) phone retail outlets selling Smartphone in eleven areas within Ibadan Metropolis. Two instruments were used for data collection, namely: Consumer Buying Behaviour Inventory and Advertising Scale. The results were analyzed using frequency counts, percentages and correlation analysis. Findings from the study revealed that there was a significant influence of advertising on consumers’ buying behaviour of Smartphones in Ibadan metropolis. Also, the result shows that there was age disparity among the buyers of Smartphones in Ibadan metropolis. The results also revealed that female customers have higher percentage use of Smartphone in Ibadan metropolis than their male counterparts. Based on these findings, it was recommended that the organisations should have long term advertisement programs that are capable of influencing consumers’ buying attitudes and to compete favourably with their competitors. It was also suggested that all ages should be encouraged to make use of Smartphones and that the age range of targeted audience must be considered while designing Smartphones and male consumers should be more encouraged.