The Focus joined Ford's C-MAX and Galaxy as top sellers in their respective segments.
Focus sold a total of 3,738 units during the year to top the sales chart, placing the nameplate 382 units ahead of its nearest competitor, the VW Golf.
The Fiesta also retained its place as one of Ireland's favourites by selling 2,151 units, a level of sales that guaranteed it a top 10 spot at seventh place.
1) Ford Focus
2) VW Golf
3) Nissan Qashqai
4) Toyota Avensis
5) Toyota Yaris
6) Skoda Octavia
7) Ford Fiesta
8) VW Passat
9) Toyota Auris
10) Renault Fluence
Eddie Murphy, Chairman and Managing Director of Ford Ireland, commented: "In a tough year for car sales, with the market down some 12 percent, we are delighted that Focus was again the number one choice for Irish motorists.
"Its great mix of stylish design and cutting-edge technologies continues to keep Focus at the top of motorists' wishlists.
"We would expect 2013 to be another challenging year in the industry, with car sales finishing perhaps in the same region as the 2012 total of 79,500.
"The new 131/132 registration system will undoubtedly help to spread the traditional January rush for the new registration plate, but it could be a year or two before the full effect of the change is felt."