AdGrok announced the acquisition on its Website on Tuesday, saying Twitter asked them to work on a "monetization platform." The company added that it had served customers on Google's AdWords platform but would stop doing so by the end of June.
"We're happy to announce that Twitter has acquired the AdGrok team. Starting today, we will be working full-time on Twitter's revenue engineering team," AdGrok said in a brief statement.
Twitter spokesman Matt Graves confirmed that two of the members of the AdGrok team were now working at Twitter's San Francisco headquarters as part of the deal. The third AdGrok co-founder has joined Twitter rival Facebook, Graves said in an emailed message.
Twitter did not disclose a price, but tech blog Techcrunch reported the deal was sealed at under $10 million.
Twitter has quickened efforts to generate revenue under the helm of new CEO Dick Costolo, introducing ways for marketers to deliver ads within the microblogging service. But the company's revenue growth has lagged some of its online peers.
Twitter is expected to bring in about $150 million in ad revenue this year, compared to Facebook's roughly $4 billion in ad revenue, according to research firm eMarketer.
Twitter, which allows people to send 140-character text messages or "tweets" to groups of followers is one of the Web's most popular social networking sites along with Facebook and Zynga, and is closely watched by investors hoping for a potential initial public offering.
In December, Twitter was valued at $3.7 billion in a $200 million funding round led by venture capital firm Kleiner Perkins Caufield & Byers. An auction of Twitter shares on the secondary market in March suggested investors were valuing the company at more than $7 billion.