Mario Rosati has been with Wilson Sonsini Goodrich & Rosati since 1971, first as an associate and, since 1975, as a partner. Mario specializes in corporate law, especially as it relates to technology companies. He serves as the managing partner of WS Investments, an investment partnership composed of the partners and associates of the firm. WS Investments has invested in a number of emerging corporations over the years.

From 1994 to 2010, Mario was an adjunct professor at the University of California at Berkeley's Haas School of Business, where he taught new venture finance. In 2012, he taught the same subject at the UC Berkeley School of Law (Boalt Hall).

Mario has sat as a judge pro-tem in the San Mateo County Superior Court. He also participated in the Innovation and Entrepreneurship Task Force to the office of the President Elect, Ronald Reagan.

In addition to the boards of the public companies mentioned below, Mario is a director of several privately held companies.