The startup works with large media companies and lets them manage and deliver video advertising across a range of products -- from Apple's iPhones and iPads, to devices running Google's Android mobile operating system, to streaming products like Xbox and Roku.
For now, mDialog will continue to operate its service, but Google said the startup's technology will eventually be folded into the search giant's DoubleClick ad-tech suite.
"Together, we're looking forward to offering content creators new and even better ways to make money from their live and on-demand content," mDialog wrote on its website. Google declined to further comment.
The buy comes as large tech companies find ad dollars increasingly shifting away from traditional display ads to other types of ad units. Google and others have been competing to remain aligned with the shift. Yahoo in February announced Gemini, an advertising marketplace for native ads, which look and feel more like editorial content, instead of being blatantly cordoned off like banner ads.
Google's attempt to bolster its online video ad offerings comes as competitors nip at its heels in other advertising areas. For example, according to eMarketer, Google's share of mobile search ad revenue dropped to 68.5 percent in 2013, from 82.8 percent the year before.
The reason for the shift, eMarketer explained, is because mobile users tend to go to specific apps when they want to find something, instead of heading to a general search engine. So, shoppers might go specifically to the Amazon app, instead of first Googling an item on their phones.