The new 200-cover restaurant, the chain's first in Western Europe, will open within the restaurant quarter at St David's Shopping Centre alongside 18 other restaurants and takeaway units.
It will also be the first of five Ruby Tuesday restaurants that brothers Gary and Stephen Mayo plan to open under the UK franchise over the next four years.
Gary said: “Ruby Tuesday is a strong restaurant concept that has successfully exported its brand and differentiates itself from other American chains in the marketplace.
"St David’s provides us with a great location for the UK launch of the restaurant as the new centre is attracting visitors from all over the UK. With Cardiff likely to become one of the top five shopping destinations in the United Kingdom, we will benefit from the footfall likely to be achieved on the back of it.”
The brothers, who also own Bryn Meadows Golf, Hotel and Spa in Caerphilly and are behind the Subway franchise in Wales, said they'd decided to make a bid for the Ruby Tuesday franchise after they saw a gap in the market for a casual dining concept.
“Ruby Tuesday is a strong restaurant concept that has succeeded to export well and reinvent itself to differentiate from other American chains in the marketplace.
"The casual dining market makes up a huge proportion of the UK economy and while growth for most brands has flattened out in recent years, there are still opportunities for a strong brand such as Ruby Tuesday," said Gary.
On top of private capital, the brothers raised £750k of funding for the £3m venture with South Wales accountants KTS Owens Thomas.
Three other restaurants - a branch of the Italian chain Prezzo and two new local concepts, Boof and Sale Pepe - are also due to open at the centre at the same time as Ruby Tuesday at St David's.
Another five deals are due to exchange in the next few weeks and will join existing restaurants which include Jamies Italian, Yo Sushi, Wagamamas and Carluccio’s.