Lewis Platt succeeded John A. Young as president and chief executive officer of Hewlett-Packard in 1990, and then succeeded co-founder David Packard as the company's chairman of the board in 1993.

It took three people to replace him, as he left HP while it was dividing into two companies, the new HP and Agilent Technologies each having their own CEOs, and Richard Hackborn serving as chairman of both for a transitional period.

On December 1, 2003, Platt was named chairman of the board of Boeing (at Phil Condit 's resignation as chairman and CEO).

Platt earned his bachelor's degree from Cornell University in 1964 and his MBA from the Wharton School of Business at the University of Pennsylvania in 1966. He was granted an honorary doctorate in Engineering Science by Santa Clara University.