The appointment follows a pitch against undisclosed agencies.
Following the appointment, Beacon will be responsible for crafting local strategies and creative work across all channels, with the first major campaign scheduled to hit the market in the second half of the year.
According to Andreas Wecke, director of Mini Japan, Beacon was selected on the strength of its creativity, know-how and "process capability".
In Japan, over 90 per cent of cars sold are by domestic brands. Although a challenger brand, Mini has however drawn double-digit growth in brand desire among local consumers who seek affordable luxury.