Autonomy, which is based in Cambridge, was set-up in 1996 and offers software solutions that identify and extract useful information from emails, telephone calls and videos. The software can be used for activities as diverse as suggesting answers for call centre workers to seeking out information to identify attempts at fraud.
Dr Mike Lynch, who founded the firm with Richard Gaunt, will net more than £500m for his eight percent stake in the firm, which is he will continue to lead following its acquisition by HP.
"This is a momentous day in Autonomy's history. From our foundation in 1996, we have been driven by one shared vision - to fundamentally change the IT industry by revolutionising the way people interact with information," said Dr Lynch.
"HP shares this vision and provides Autonomy with the platform to bring our world-leading technology and innovation to a truly global stage, making the shift to a future age of the information economy a reality."
Léo Apotheker, HP's CEO, said Autonomy presented an opportunity to accelerate the strategic vision to decisively and profitably lead a large and growing space.
"Autonomy brings to HP higher value business solutions that will help customers manage the explosion of information."
The deal is part of HP's strategy to focus on software. As part of this strategy HP confirmed it is to stop making tablet PCs, phones and computers.