The checks were carried out to ensure that all clubs qualified to play in the Premier Division satisfy an agreed set of criteria which covers areas such as finances and administration, regulatory compliance, player development programmes and ground facilities.
All clubs within the Premiership have to achieve the agreed criteria and all First Division clubs seeking promotion are also measured by the same standard of criteria.
Clubs involved in the process have now been informed of the result of the WRU audit.
All 14 of the current Premiership clubs achieved the criteria standards. They are: Aberavon, Bedwas, Bridgend, Cardiff, Cross Keys, Ebbw Vale, Glamorgan Wanderers, Llandovery, Llanelli, Neath, Newport, Pontypool, Pontypridd and Swansea.
The First Division clubs which applied for qualification and passed the criteria are: Beddau, Carmarthen Quins, Merthyr, Narberth and Newbridge.
WRU Head of Rugby Performance and Development Joe Lydon said: "This announcement is further recognition of the ambition and hard work that continues to exist across the club game in Wales.
"All clubs from outside and within the Premiership who have successfully passed the criteria should be congratulated and all associated with Welsh rugby can look forward with confidence knowing that great strides are being made to ensure the standards and performance of the Principality Premiership are being raised both on and off the pitch.
"The First Division clubs that have passed the criteria reflect the ambition and drive that exists in that Division to improve standards on and off the pitch - and reach the Premiership."
Chris Clarke, spokesperson for the Premier clubs, said: "The Premier clubs fully support the WRU and the drive to maintain and enhance the administration and facilities of Welsh Premier clubs.
"This has been demonstrated by the considerable expenditure and investment of some clubs to advance those standards for sponsors, members and visitors to enjoy rugby at Premiership grounds."