As technical director, Long will be responsible for designing and delivering performance strategies across both the men’s and women’s games for both the national and regional teams.
He will also play a key role in any national coaching appointments.
Long said he wanted to develop a “uniquely Welsh performance model and DNA” to restore a winning mentality across the game in Wales.
He added: “This is an important time to join Welsh rugby, we are in a period of transition but bold steps towards a successful future have already been taken.”
WRU director of rugby Dave Reddin said: “Rhys will play a key role in defining and embedding a Welsh rugby DNA in the principles of how we play, coach and our Welsh identity across both our men’s and women’s pathways and senior teams.”