After more than a decade at Google, Pichai was named CEO of the company when it was re-organized in August 2015 into a unit of Alphabet.
Pichai "helped lead the development of key consumer products which are now used by over a billion people," the company said in a statement announcing the appointment.
The addition of Pichai adds another company officer to the board, which already includes Google co-founders Larry Page, now Alphabet CEO, and Sergey Brin, president, and chair and former CEO Eric Schmidt.
Diane Greene, head of Google's enterprise and cloud unit, is also on the Alphabet board.
That's a total of 5 insiders on a 13-person board, which is a fairly high proportion of insiders compared with other major tech companies.
By way of comparison, Apple and Amazon each have only 1 insider on their boards (CEOs Tim Cook and Jeff Bezos respectively) and Microsoft has 3 insiders on its 12-person board (including LinkedIn founder Reid Hoffman, who joined after Microsoft bought LinkedIn). Facebook's board is more heavily stacked toward insiders, with 3 out of 8 (including WhatsApp founder Jan Koum).
Generally speaking, boards of directors are meant to represent the interests of shareholders in cases of conflict with company leadership, although the multiclass share voting structures used by some tech companies, including Alphabet and Facebook, concentrate voting power in the hands of founders, giving significantly more power to those founders.
Alphabet shares are down after hours after the company reported Q2 earnings that beat expectations.