As a result of new and improved technologies and techniques, advertising has witnessed some rapid changes over the years. One of such changes is online advertising. Marketers and businesses are shifting focus to online advertisement due to the emergence of information technology and cheap access to the internet. Other reasons why marketers prefer online ads to traditional forms of advertising include cost, wide coverage, the interactive nature of online ads and its appeals to the younger population. However, the extent to which these online advertisements affect the purchase behaviour of consumers has not been extensively explored. In view of this, the study sought to examine the perception of internet users towards online ads and how such perceptions influence their purchasing behaviour. To achieve this objective, a survey was conducted among the students of Bolgatanga Technical University (BTU) to represent the population of online users. A total of 42 of these respondents were conveniently sampled for the study. A quantitative method was used where a descriptive and regression analysis were conducted to analyse the data in order to meet the objectives of the study. The findings revealed that the respondents generally have a positive perception/attitude towards online advertising. For instance, the respondents perceive online ads as credible, less intrusive, informative and entertaining. The study further revealed that the perception of users towards online ads significantly influences their purchase intentions. The study recommends that the marketers and online advertisers must design online ads that are credible; informative, entertaining and less intrusive to attract users.