The extension of the relationship between the two firms will see HP manage Unilever's technology infrastructure in the Americas, Asia, Africa, Turkey and the Middle East.
Operating as a single point of contact for Unilever's enterprise computing environment, HP will work with Unilever's strategic partners, including SAP, Microsoft and BT, to help reduce costs and ease the integration of new applications.
HP also will manage third-party contracts within Unilever's technology environment.
Through the agreement, HP will provide management of Unilever's IT processes and services, including corporate data centres, messaging and directory services.
It also includes internet and intranet systems hosting, disaster recovery services, and the outsourcing of 4,500 multi-vendor UNIX and Windows servers and storage environments.
The deal will also see around 250 Unilever employees transferring to HP.
"In this space, HP has demonstrated a distinctive collaborative approach combined with a clear expertise in the delivery of global services," said Neil Cameron, chief information officer at Unilever.
"This agreement is a natural extension of our current relationship. The intention between both parties is to leverage HP's scale, expertise and industry leadership to ensure Unilever has access to world-class technology at substantially lower costs," he said.