To create a modern hotel the Malmström family put great effort in hospitality, quality as well as great design. The hotel is designed by the internationally renowned architect Per Öberg, who combines the Hotel Diplomat heritage with an airy, bright, and contemporary Scandinavian style.

The 130 rooms and suites are designed and decorated by the co-owner Anna Cappelen, in collaboration with the interior designer Helene Follin from HOS Haga. The rooms are inspired by the unique Art Nouveau building, blending traditional elegance with contemporary design.

The rooms are decorated with exclusive furniture from the Italian manufacturer Meridian. The textiles are from selected high-end designers such GP & J Baker, Vaughan Designs, Dedar, Designers Guild, Romo, Zoffany as well as the Swedish producers Svensk Tenn and Astrid.