Wales internationals Alun Wyn Jones, Dan Biggar (both Ospreys), Scott Williams (Scarlets) and the uncapped Gareth Anscombe (Blues) have all signed Welsh Rugby Union dual contracts.
It means there are now 12 players on the contracts which are funded 60% by the WRU and 40% by the regions.
The length of the contracts has not been disclosed.
"[They] represent a cross section of experience, but each [has] proven talent," said coach Warren Gatland.
Second row Jones, 29, has played 88 matches for Wales and captained the British and Irish Lions to their historic Third Test victory over Australia in 2013.
His Ospreys team-mate Biggar, 25, has established himself as Wales' first choice fly-half while 24-year-old centre Williams made a try-scoring appearance off the bench in the 23-16 win over Ireland.
Blues outside-half Anscombe has been a non-playing member of the Wales squad during the Six Nations after moving to Cardiff from New Zealand in November, 2014.
The quartet follow Rhys Webb (Ospreys), Sam Warburton (Cardiff Blues), Dan Lydiate (Ospreys), Jake Ball, Samson Lee, Rhodri Jones (all Scarlets) and Tyler Morgan and Hallam Amos (both Newport Gwent Dragons) in signing dual contracts..
"Within the group of 12 we have signed a mixture of emerging talent and players who have secured reputations for excellence through their appearances for their Regions, Wales and the British & Irish Lions," added Gatland.
"The strength of the group is of great benefit to professional rugby in Wales and we are looking forward to working closely with the Regions and these players in the years ahead."