The legal offering is supported by the expertise of their consultancy and training business, Consult Capital, which specialises in health and safety, HR, management and leadership support.
Capital Law's Sion Clwyd Roberts, who will be managing the relationships with both clubs, said: "We're extremely pleased to be working with two of Wales' top sports clubs, both of which have aspirations to progress at home and internationally. If we can contribute in some small way to both teams' success on the field through assisting their off the field management, we'll be very proud."
Capital's team has a strong sports industry background, having worked with, for instance, the International Rugby Board, the FA, Football Association Wales, British Boxing Board, Glamorgan Cricket, the World Rally Championship and Cardiff Devils.
Speaking about what lies ahead, Sion commented: "It's undoubtedly going to be a busy year as both clubs continue to seek success. We are particularly excited about the prospect of Cardiff City's promotion to the Premier League and all of the added benefits this would bring to both the club and the city region as a whole.
"It's also going to be an exciting season for the Blues. With some experienced new signings, including the solid foundation an international front row will bring, as well as a great crop of youngsters coming through their Academy, the Blues have created a strong platform for success and we're looking forward to working with them. "
Richard Holland, Cardiff Blues' Chief Executive, says: "we've known Capital Law for quite some time, and we like the way they work. There are several areas we're looking forward to them helping us with, and hopefully our association will contribute to the continued growth of their brand too."
Chef Executive and Acting Chairman at Cardiff City FC, Simon Lim commented: "Building the relationship with Capital Law has proved an excellent move for Cardiff City Football Club. They've advised us in a number of specific areas so that we're in a strong position to progress, bringing fresh perspective to certain challenges. Capital Law understands the club and their team care about our success, which was an important factor for us."