Mauretania was designed to suit Edwardian tastes. The ship's interior was fitted out in co-operation by two notable London design houses – Ch. Mellier & Sons and Turner and Lord, with twenty-eight different types of wood, along with marble, tapestries, and other furnishings such as the stunning octagon table in the smoking room. Wood panelling for her first class public rooms was supposedly carved by three hundred craftsmen from but this seems unlikely, unnecessary and was probably executed by the yard or subcontracted, as were the majority of the second and third class areas. The multi-level first-class dining saloon of straw oak was decorated in Francis I style and topped by a large dome.
A series of elevators, then a rare new feature for liners, with grilles composed of the relatively new lightweight aluminum, were installed next to Mauretania's walnut grand staircase. A new feature was the Verandah Café on the boat deck, where passengers were served beverages in a weather-protected environment.