All of Wales' Aviva Premiership-based players will be made available for the autumn Test opener against Australia in Cardiff on November 5.
Premiership Rugby has confirmed the one-off move, describing it as a "gesture of flexibility".
It means that Wales' interim head coach Rob Howley can call on the services of Northampton wing George North, Harlequins centre Jamie Roberts, Gloucester flanker Ross Moriarty, Exeter prop Tomas Francis, plus Bath forwards Luke Charteris and Taulupe Faletau, although number eight Faletau is currently injured.
Premiership Rugby - the umbrella organisation for England's 12 Aviva Premiership clubs - do not normally release non-England players who ply their trade in the Premiership for Tests that fall outside World Rugby's autumn international window.
The Australia game is outside of that official three-weekend slot, with Wales also facing Argentina, Japan and South Africa in November.
The Premiership Rugby decision applies to all nations in Test action on the weekend of November 4-6. The only other Tests that weekend are Ireland against New Zealand in Chicago and Japan versus Argentina.
"As a gesture of flexibility, the Premiership Rugby clubs will release their players outside the approved Test window for matches on the weekend of 4-6 November," a Premiership Rugby spokesperson told Press Association Sport.
"This comes as we continue deliberations on a new post-2019 global season structure to find an appropriate balance between club and international rugby.
"We are showing flexibility to help a number of unions who have decided to play on this particular weekend, but we must stress this is a one-off variation to the allowed window while discussions continue."
Premiership Rugby's stance is a huge boost for Howley as Wales look to address a run of 11 successive defeats against Australia.
Howley is at the helm this season while head coach Warren Gatland concentrates on British and Irish Lions business building towards next summer's three-Test New Zealand tour.
And the certainty of game-breakers like North and Roberts being available will be of huge benefit as preparations begin for the Wallabies fixture in 12 days' time.