Warren Gatland's side will head to the Eastern Cape ahead of the test series and kick off their tour at the Nelson Mandela Bay Stadium in Port Elizabeth.
It will be a chance for final preparations ahead of the first test against the Springboks and Gatland is delighted to have secured the fixture.
"It's great that we are able to confirm a midweek fixture against The Eastern Province Kings in addition to our two test matches," he said.
"The match in Port Elizabeth will allow us to get a game under our belts at the start of what will be a very tough tour and help us hit the ground running.
"We will be looking to take a slightly bigger squad and this gives us the opportunity to look at everyone and give the whole squad game time which is important ahead of next year's Rugby World Cup.
"It is an important tour for us and this game will give us the best start before the tests against the Springboks."
Wales will travel to Growthpoint Kings Park in Durban for the first test against the Springboks on Saturday 14th June, kick-off 5.05pm (local. 4.05pm BST) and face the two-times Rugby World Cup winners ('95, '07) a week later in Nelspruit at the Mbombela Stadium (also 5.05pm local).
The home side themselves will warm-up for the series by facing a world XV on the 7th June.
"We would like to thank the Eastern Province Kings and the South African Rugby Union for agreeing to this fixture and allowing us the best preparation ahead of the test series," said WRU Group Chief Executive Roger Lewis.
"Our stated aim has been to take every opportunity to test ourselves at the highest level and this summer will be stern test for the squad.
"The midweek fixture not only allows Warren and his team to prepare for the rest of the tour but also provide useful insight into the strength of our squad as we look ahead to the 2015 Rugby World Cup."
Wales tour fixtures:
Tuesday, 10 June: Eastern Province Kings v Wales, Nelson Mandela Bay Stadium, Port Elizabeth, 19.00 (local)
Saturday, 14 June: Springboks v Wales, Growthpoint Kings Park, Durban, 5.05pm (local).
Saturday, 21 June: Springboks v Wales, Mbombela Stadium, Nelspruit, 5.05pm (local).
Note: Any broadcast information for the midweek fixture against Eastern Province Kings will be available in due course.