The deal provides a significant boost to Welsh rugby and allows Principality Building Society the naming rights to the match, which serves as a mouth-watering appetizer to Wales' two-match summer tour of New Zealand a week later, and will provide a raft of other benefits and offers to its 500,000-plus members.
Through a range of promotions running alongside the partnership, the Society's members will have the opportunity to not only win tickets to the game, but also meet the Wales team, visit training sessions and even present the Prince William Cup to the winning side on match-day.
The Principality Building Society already has a long association with the WRU, having sponsored the Welsh Premiership since 2005 and previously the WRU's main knock-out cup competition from 2001 to 2003.
Formed in 1860, the Welsh building society is 21 years older than the WRU and is as much a part of the fabric of Wales as the national game itself.
The WRU has already sold in excess of 40,000 tickets for the clash with the Springboks on what could be an historic day for head coach Warren Gatland and his men.
The Principality Building Society Summer Test celebrates the 10th anniversary of the only time Wales have beaten the Boks in 23 attempts, the 29-19 victory at the Millennium Stadium's inaugural match on 26 June, 1999 - (Wales have lost to South Africa 21 times since 1906, the seventh meeting between the two sides in 1970, at the national stadium in Cardiff, ended in a 6-6 draw).
"This new partnership with Principality Building Society really is the icing on the cake of what could be a truly historic and inspiring day for Welsh rugby," said WRU Group Chief Executive Roger Lewis.
"Warren and his players have a gilt edged opportunity to repeat history against the current world champions and lay down a marker ahead of an equally tough two-Test tour of New Zealand.
"I'm sure the drama and potential which surrounds this fixture has been part of the draw for the Principality Building Society whose new partnership with the WRU sees them involved with us at international level for the first time, though they have a long history themselves of supporting Welsh rugby.
"We had the Principality Cup for three seasons from 2001 and have been partners with the Principality Premiership since 2005, an association set to continue to run into 2011, and now we have the Principality Building Society Summer Test as they celebrate their 150th year in existence.
"We are two organisations which are right at the very heart of Wales and our growing association is to the mutual benefit of the society's members and Welsh rugby fans alike."
Commenting on the partnership, Graeme Yorston, Chief Operating Officer at Principality Building Society, said: "We are thrilled to support this special celebration fixture in our 150th anniversary year, providing welsh fans with a unique opportunity to see the summer tour squad put through their paces before they jet off to New Zealand.
"The Society shares a long and proud history with the Welsh Rugby Union, which we believe is central to the culture and heritage of Wales. The Principality Building Society Summer Test is the perfect mix of tradition and innovation which will capture the enthusiasm and patriotism of people across the country.
"In our very special anniversary year we wanted to say a heartfelt thank you to the people of Wales and our support of one of the biggest, most unique events on the welsh calendar this year, is our way of saying Diolch!"
Wales head coach Warren Gatland added: "I'd like to welcome the Principality Building Society to international rugby and I obviously hope we can do justice to their new partnership with the WRU with a performance the nation can be proud of.
"We have said all along that we want to play the best teams in order to better ourselves and they don't come much bigger than the world champions on home turf in front of a bumper Millennium Stadium crowd baying for a win.
"Wales, the WRU and now the Principality Building Society have a tremendous opportunity to make history on 5th June and we are all very much looking forward to it."
Tickets for the Wales v South Africa fixture are currently on public sale and are selling in their hundreds on a daily basis.
With more than 41,000 gone over a month in advance of the sizzling summer afternoon clash against the world champion Springboks, fans are already voting with their feet so interested parties are advised to act quickly.
Priced at £25 per person or £80 for a family ( 2 adults, 2 children) tickets for the 'Principality Building Society Summer Test' can be purchased from at the WRU's Cardiff Arms Store (No 8 Westgate Street, Cardiff); via Ticketmaster (tel 08442 777888, www.ticketmaster.co.uk), Ticketline (02920 230130, www.ticketlineuk.com) and via the WRU Official Website www.wru.co.uk/tickets.
The remaining WRU hospitality packages can be snapped up from £119 for the 'SA Gold' package and fans should act fast to secure the hottest tickets via the official website www.millenniumstadium.com.
Further hospitality information is available online for all packages including the 'Platinum Suite' at £229 and the recently launched 'Springbox Suite' at £139 after popular demand.