The ImageAds service is intended to make advertising on the search engine, which until now has only offered text-based ads, a more attractive and effective channel for brands. Google is likely to charge a premium for the service.
ImageAds will be tested this week and will be built into its existing AdWords system. Images will appear alongside searches in one of four formats: banners, leaderboards, skyscrapers and in-line rectangles.
Publishers that have signed up to Google's AdSense programme will be able to opt in or out of receiving image ads.