Online advertising plays a crucial role in shaping consumer buying behavior by influencing awareness, preferences, and purchase decisions. Building on the theory of planned behavior (TPB), this research examined the direct influence of online advertising dimensions of informativeness, credibility, creativity, entertainment, interaction, and integration on consumer buying behavior in Saudi Arabia, emphasizing the moderating impact of brand image. Using a quantitative research method, convenience sampling technique, and a survey questionnaire, 200 valid samples were collected and analyzed to fulfill the research objectives. The structural equation modeling findings showed that informativeness, credibility, creativity, and interaction had a significant influence on consumers buying behavior, while entertainment and integration had no significant impact. The moderating analysis indicated that brand image only strengthens the impact of informativeness, credibility, and interaction on consumer buying behavior. The findings of this research validate the importance of online advertising in influencing consumers' buying behaviors and urge online stores or e-commerce platforms to consider the informativeness, credibility, and interaction dimensions of their online advertising.