Whitman joined Hewlett-Packard in 2011 and oversaw the company's split into two brands. She remained as CEO at the newly streamlined HPE, prioritizing cloud services and spinning off product and consumer hardware to HP Inc.
Whitman is leaving a decidedly different company than the one she joined six years ago, having pushed for the company's split.
"I believe the future belongs to the fast," Whitman said. "And it was just too big and too cumbersome and competed in too many markets to do the very best job in all of them."
Her tenure at HPE saw a ramping up of acquisitions — eight in the last two years, she told CNBC.
Neri has been with the company since 1995, working his way up to the company's top ranks. Whitman will remain on the board and Neri will join it, the company said.
"[Neri] and I have been joined at the hip in deciding about those acquisitions," Whitman said. "He's been really my right-hand executive for well over four years."
Whitman said she is not sure of her next step, but that any next CEO position would have to be "exactly the right opportunity."
She reportedly spoke to Uber about a CEO position after the ride-hailing company booted founder Travis Kalanick in June. The company selected Dara Khosrowshahi.
Whitman told analysts Tuesday that she'll be taking a little downtime and said there's "no chance" she will join a competitor to HPE or HP.