The 16 participating teams have been confirmed, with Wales Students and RGC 1404 joining the 12 Principality Premiership sides and the top two sides from last season's SWALEC Championship, Ebbw Vale and Bargoed.
It will be an all-day event - gates will open at 9.30 am, the first match will kick off at 10.20 with the Cup final due to take place at 6pm.
Wales Sevens head coach Paul John said:
"Sevens rugby is certainly on the up on a global level - the HSBC Sevens World Series is growing all the time, the Rugby World Cup Sevens has just taken place and Sevens will be part of the next Olympic Games - so it's important to continually raise the standard of the players we are producing in Wales.
"We are working hard with schools, colleges and universities to increase the amount of Sevens that is played at age group level - and it's great that a Wales Students side will be competing on the day - but it is key to have a vibrant sevens club scene too.
"Most of our Wales Sevens players come from the Principality Premiership so not only will this new tournament expose new players to top class Sevens competition, but our core Sevens squad members will be representing their club sides on the day so we should see some of the best sevens rugby Wales has to offer."
John, who has just returned from Moscow with his Wales Sevens squad having reached the last eight of the Cup competition, believes the introduction of the National Sevens is a necessary move with the standard of international sevens teams ever improving.
"International Sevens sides are constantly raising the bar and if we are to compete consistently and retain our place within the top echelons of the game, we need to constantly find new ways to blood players and prepare them for the demanding realities of the international seven a side game.
"Sevens rugby is compelling viewing and conducive to producing a fun environment for supporters of the game and fans won't be disappointed if they turn up on Bank Holiday Sunday for a day of high quality, high tempo rugby."
Benn Morris, Business Development Manager, Heineken UK said, "Heineken UK in association with Foster's are proud to sponsor the first WRU National Sevens at the prestigious Cardiff Arms Park. Foster's, a brand with history and provenance which celebrates its 125th anniversary this year and we are excited to support this great rugby occasion and to provide a great, fun consumer experience. Good call since 1888!
There will be something for everyone on the day, including a family fun area with face painting, rugby skills activities, bouncy castles, live music and more.
Tickets are on sale now at just £10 for adults, £5 for Under 16s and £20 for a family ticket (2 adults, 2 children). Go to wru.co.uk/nationalsevens to purchase tickets or call 0844 8471881 (Ticketmaster) or 02920 230130 (Ticketline). Personal callers can also purchase tickets from the WRU shop, 8 Westgate Street or from Ticketline, 47 Westgate Street.