The acquisition of Ono, which offers high-speed broadband and pay-TV to 1.9 million customers in 13 regions of Spain, builds on Vodafone's purchase of Kabel Deutschland for around £6.5 billion last summer.
Vodafone's latest swoop comes as it looks to spend some of the proceeds of its 130 billion US dollar (£78 billion) sale of its stake in US mobile phone operator Verizon Wireless.
Vodafone is growing strongly in emerging markets such as India, but its European business has been weighed down by economic conditions, competition, and regulator-imposed price changes.
And the sector's focus has been shifting towards "quad play", which involves providing bundles of phone, broadband, mobile and pay-TV services.
Vodafone chief executive Vittorio Colao said: "Demand for unified communications products and services has increased significantly over the last few years in Spain, and this transaction will accelerate our ability to offer best-in-class propositions in the Spanish market."