Millennium Stadium Chief Executive Paul Sergeant said: "The date of Saturday 13 May 2006 is now firmly secured in our diary and we have signed an agreement to that effect.
"The FA have every intention of staging the showcase event at Wembley and we wish all those involved in the construction of Wembley every success. These projects can be very complicated, but it is in everyone's interests that the new Stadium goes to plan.
"However, it makes perfect business sense for the FA to have a firm back-up venue for the FA Cup Final and this agreement alleviates any pressure on the governing body should Wembley not be ready. This is a case of good planning and good football sense on the part of the FA.
"It would be great to have the FA Cup Final back in Cardiff one more time, and this news is testament to the Millennium Stadium's success in hosting the past five FA Cup Finals. Football fans, and everyone involved in the game, can rest assured that we will deliver another fantastic day should we get the green light."
The last five years have been an emotional rollercoaster on and off the pitch for RGC1404. Promotion to the Principality Premiership was the culmination of five years of hard work and investment in North Wales. WRU TV caught up with prop Joe Simpson, who was one of the first intake of WRU North Wales Academy players in 2010.
Ebbw Vale captain Damien Hudd picked up the biggest accolade of the night at the 11th Principality Premiership Awards Evening held at Principality Stadium, after leading his side to the title for the first time.
Wales assistant coach Robin McBryde is predicting a tough battle against England on Sunday despite the fact they may not be considered to be at full strength. Players will be out to impress Eddie Jones which makes England a dangerous proposition, he says.
Wales U20 captain Tom Phillips and performance psychologist Dr Rich Neil explain why spending three days at Monmouth RFC has further strengthened the togetherness of the squad ahead of the #WorldRugbyU20s