Saints fly-half Dan Biggar will start for Wales in their World Cup quarter-final against France on Sunday (kick-off 8.15am UK time).
Biggar had been forced off against Australia and Fiji due to head injuries.
But he has shown no signs of concussion since the win against Fiji and will now be able to resume in the 10 shirt after missing the game against Uruguay.
A Wales statement read: "Following Dan Biggar’s concussion sustained in an accidental collision in the match against Fiji, the WRU have worked collaboratively with World Rugby to deliver the highest level of care for Dan.
"Dan has remained symptom free since the game and has completed the graduated return to play with no issues.
"Management has included MRI scanning and two consultations with a globally renowned independent concussion consultant from Australia.
"We are pleased to say that given that all return to play protocols have been met, imaging being normal and ratification from the independent concussion consultant, that Dan has been deemed fit to play.
"The WRU continues to ensure that player welfare is at the fore of our decision making processes and is independent of the any team or competition."
Elsewhere, Courtney Lawes and Lewis Ludlam are set to be involved for England in their last-eight tie against Australia on Saturday (kick-off 8.15am UK time).
Lawes starts in the second row, while Ludlam is among the replacements.
But there is no place in the matchday 23 for centre Piers Francis.
Cobus Reinach has not made the cut for South Africa's clash with Japan on Sunday, despite scoring the fastest ever World Cup hat-trick in a recent win over Canada.