The partnership includes a five-year extension to the original deal, which Compass signed when the stadium opened in 1999.
The new terms will run until 2024 and include the Millennium Stadium's acquisition of the kitchen and catering facilities originally installed by Compass on the stadium site at the time of its creation.
Matthew Thompson, managing director of sport, leisure and hospitality at Compass Group UK & Ireland, said: "Compass Group has a very positive relationship with WRU and the Millennium Stadium and I am pleased that we could forge a new deal that will provide significant financial support for rugby in Wales."
The Millennium Stadium and Compass intend to use the deal as a springboard towards increasing the volume of major sports, cultural and leisure events as well as conferences and other non event day business on the stadium calendar.
Steve Phillips, group finance director of WRU Group, said: "The new deal will provide Millennium Stadium with improved profitability per event and will align the stadium with comparable stadia in commercial terms."
By Emily Manson
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