Karnstedt was most recently an executive-in-residence at Redpoint Ventures, an investor in Efficient Frontier.
He is replacing Beriker, who held executive positions at the company since April 2007 and was its president and chief executive from February 2008 until March 2009.
Prior to Redpoint, Karnstedt served as senior vice-president of Yahoo!'s North American sales division, with responsibility for more than $3bn (£2.04bn) in revenue. During his tenure at , he successfully led the integration of the search and display sales teams into one central unit.
Ellen Siminoff, chairman of Efficient Frontier's board of directors, said: "We feel incredibly fortunate to have someone of David's calibre join Efficient Frontier at this point in the company's life cycle.
"David's extensive experience in the internet space -- specifically search -- will be a huge asset as he leads the company forward."
Karnstedt led the direct sales team at search company Overture Services prior to joining Yahoo!. He also served as vice-president and general manager of Alta Vista, where he was responsible for the consumer business.
Prior to Alta Vista, Karnstedt served as an advertising director at Wired Digital where he helped to develop some of the first advertising models on the web.
Karnstedt said: "As the leading global search engine marketing company, Efficient Frontier has built tremendous assets, including its technology platform, a global presence and a great team.
"I plan to build on these key assets by expanding the company's leadership in search, diversifying into complementary product offerings and increasing its global presence. I am pleased to lead the company into its next phase of growth."
.jpg)
.jpg)