The largest private residential ship/yacht is supposed to be currently under construction with the DIV Group/Brodosplit. If you know anything about these types of ships you would know that "The World" is the largest residence ship around at present. The 293-meter "Njord" will effectively end this when it is pegged to be completed by 2024. They are calling it a residence yacht but, lets just call it a small residence cruiseship. Espen Oeino is the designer of the exterior while FM Architettura is the interior designer. 118 private residency suites are available.
Another designer has been brought on to design some of the interiors of this residensea ship/yacht. London-based studio Taylor Howes. Here is a rendering credits to Taylor Howes.