We tested the heuristic processing of online advertisements embedded in a mobile news site. Based on the bias hypothesis of the heuristic-systematic model (HSM) of information processing, we investigated whether the advertisement format (i.e., banner vs. pop-up) and sexual content serve as heuristic cues. Specifically, we looked for heuristic cues negatively associated with the evaluations of online news readers, including the credibility of the news agency and the news content, their perceived importance of and interest in news stories, and their intention to revisit the news website. The results of online experiments indicated that participants’ perceived credibility of news articles, perceived news importance and interest in news stories were negatively associated with the appearance of online advertisements showing sexually provocative content in the news stories. However, we found no association among the advertisement format, perceived credibility of the news agency and intention to revisit a news website. Our findings suggest that an advertisement featuring sexual appeals in mobile environments can function as a negative heuristic cue.