In a filing Thursday with the Securities and Exchange Commission, Cisco said that Fiorina will remain on the company's board only through its upcoming annual meeting, which is scheduled for Nov. 11.
"It was a personal decision," Rebeca Robboy, an HP spokeswoman, said of Fiorina's move.
The two companies compete in some areas, with HP having its ProCurve line of networking gear, but have also been partners in other areas.
HP downplayed the idea that Fiorina's departure was a sign of increased competition between the two companies.
"HP and Cisco look forward to the opportunity to develop a new and broadened partnership," Robboy said.
In 2001, Ciscoa deal to use several of HP's high-end Superdome servers in for its own internal network. Fiorina earlier that year.
Fiorina has also served previously on the boards of breakfast cereal giant Kellogg and pharmaceutical maker Merck.