The website link at www.wru.co.uk/tickets which closed last Thursday, invited fans to join a priority waiting list for access to any tickets unclaimed by WRU member clubs and debenture holders.
Sell-out crowds are expected when Warren Gatland's Wales face the three teams in blue, Scotland (February 13), France (February 26) and Italy (March 20), as they chase their third championship title in six seasons.
"The fans are an important part of the team and we will be looking forward to three home games with the Millennium Stadium full to its rafters," said Wales coach Warren Gatland.
"There is nothing like looking up from the pitch to a sea of red to inspire a player, we have three tough matches in Cardiff this year and the crowd will have an vital part to play."
WRU Head of Group Compliance Julie Paterson introduced pre-registration for fans following a review of ticketing systems over the past three seasons.
She said: "The pre-registration process allows fans who struggle to secure access to match tickets to register their interest in our team and the championship and get the first chance to buy any tickets that are unclaimed by our member clubs."
"This system does not take your money at the point of registration and allows members the option to pay for any unclaimed tickets prior to the games. Pre-registration also helps to deter fans that may feel tempted to purchase tickets from sources other than a recognized established agent."
At the point of registration fans were asked for their name and contact details only and will today be given a passcode to access and pay for tickets to the games when they are released.
Julie added: "Record numbers of fans, over 27,000 this season, have pre-registered for the opportunity to see Wales play the 'three Blues' at the Millennium Stadium, compared with the 12,000 people that pre-registered for last year's championship."
A limited number of tickets for the RBS 6 Nations at £25, £46, £59, £65 and £69 will be released tomorrow to the pre-registered list via email instruction. Any remaining tickets will go on public sale at midday on Monday 18 January via www.wru.co.uk
Tickets are also available from the WRU website for Wales Under 20's and Wales Women's home games against Scotland, France and Italy from £5.
Millennium Stadium hospitality packages for the RBS 6 Nations are available from £249 plus vat per person at www.millenniumstadium.com.
Saturday 6th February
14:30 - Ireland v Italy
17:00 - England v Wales
Sunday 7th February
15:00 - Scotland v France
Saturday 13th February
14:00 - Wales v Scotland
16:30 (17:30 local) - France v Ireland
Sunday 14th February
14.30 (15:30 local) - Italy v England
20/21 February - Rest Weekend
Friday 26th February
20:00 - Wales v France
Saturday 27th February
13:30 (14:30 local) - Italy v Scotland
16:00 - England v Ireland
6/7 March - Rest Weekend
Saturday 13th March
14:30 - Ireland v Wales
17:00 - Scotland v England
Sunday 14th March
14:30 (15.30 local) - France v Italy
Saturday 20th March
14:30 - Wales v Italy
17:00 - Ireland v Scotland
19:45 (20:45 local) - France v England