The mobile company will be the first sponsor of the chart show, which runs across 125 commercial radio stations including 95.8 Capital FM and the Heart network.
The sponsorship, which starts on 3 November, will be used to promote Vodafone Freebees, a new service which rewards Pay As You Go customers each time they top up.
Vodafone is spending £10m on promoting its pay-as-you-go products in the run up to Christmas.
The 12 month partnership sees the show renamed the “Vodafone Freebees Big Top 40.”
Further promotion will feature on-air, and across mobile and online platforms, with six homepage takeovers throughout the year.
It has taken Global Radio over a year to find a sponsor for the show, which includes real-time sales from iTunes. Apple is known for being very specific about the brands it wants to be associated with.
Global was slammed by Ofcom last year for excessive plugging music download service iTunes.