"The average attack, you get 90 percent of the data you want in like nine hours, and yet most of the companies don't find out for three to four months," he said.
The warning comes after a year of high-profile cybersecurity breaches that were a disaster for many businesses.
The attack on Hollywood movie studio Sony Pictures – which was blamed on North Korea – saw movie scripts, sensitive information about film stars and private conversations between executives leaked.
Investment bank JPMorgan was hit with two attacks last year, while a number of flaws in internet security and mobile software were found.
The World Economic Forum has flagged up cybersecurity as one of 2015's biggest risks and company bosses are putting an increasing focus on shoring up their defences.
Chambers said that an increasing number of devices will be connected to the internet in the so-called Internet of Things making the security threat even more actue.
"You're going to see every country, every city, every company, every car, every house, every wearable become digitized," he said.
Laying out Cisco's future ambitions, Chambers said the company will focus on cybersecurity and aim to become "number one" in the sector.