Blues Region champions Merthyr Youth defeated North Wales champions Rhyl Youth 21-9 while in the second semi-final, Ospreys region champions Bridgend Athletic Youth overcame the challenge of Dragons region champions Blackwood Youth, to run out 27-3 winners and cement their spot.
Since the RAF Careers Youth League sponsorship launched in September 2008, more than 4,500 Youth League players have spent the last year competing in the new RAF Careers Youth League, with the ultimate goal of reaching the final.
Saturday's event will mark the culmination of a season of hard work from players, coaches and officials and will provide a great opportunity to showcase some of Wales' finest emerging young talent. Ambassador for the RAF Careers Youth League and Welsh International Tom Shanklin will watch the drama unfold on Saturday.
"Many of today's professional players started out at grass roots level, so youngsters getting coached now and those playing in Saturday's final could be playing for Wales in a few years' time", Shanklin said. "I may not have been able to come this far without the benefit of good coaching at an early age. That's why I always try to help out when I'm offered the chance to get involved in the RAF's coaching clinics."
Ospreys scrum-half Mike Phillips played his youth rugby at Whitland RFC from the age of 15 to 19. Now at the age of 26, Phillips has carved out a hugely successful professional career. But he credits his youth rugby run at the Carmarthenshire club with providing him with the real determination to succeed.
"My time at Whitland was a massive turning point for me," he said. "I used to go and watch my brother, Rob play for them and I soon joined myself. I enjoyed my rugby at Whitland so much that I began thinking seriously about making a career out of the game.
"It is vital to have a good foundation in the game - and to enjoy it - especially if you are going to go on to make a successful career out of rugby. We're very lucky to have such a strong youth structure in Wales as it provides you with the fundamental core skills that you carry with you throughout your playing career."
Group Captain Gordon Bruce, Head of Recruiting for the Royal Air Force says: "Both teams who have reached the RAF Careers Youth League final have demonstrated commitment, discipline and drive - qualities that will help them achieve success in life both on and off the pitch. The players, as well as those who have competed throughout the season, should be proud of their achievement."
The DC Thomas Cup final will precede the RAF Careers Youth League final at the Millennium Stadium on Saturday, with Cardiff Schools Under 11 taking on Llanelli Schools Under 11 at 12.30pm.
Entry to both events is free of charge via Gate 3 on Westgate Street.