While the architectural works on the exterior and interior were being finalized, the architect Nikola Krasnov began to create an interior design for the Assembly. The design consisted of plans for furniture, lights, carpets and drapery, detailed textual descriptions, as well as the exact ground plan of the furniture arrangements. Every room, regardless of its importance and purpose, was defined accurately in the plan, so that today it is possible to perform the authentic reconstruction of all the premises in the parliamentary edifice.

Special attention was dedicated to the interior of the most important premises in the Assembly. These are: the big and small plenary halls, the great hall along with the four committee halls around it, the library, the chairperson's and vice-chairperson's offices, the diplomatic salon and the deputy clubs' premises.

In the building of the Assembly there are two groups of furniture. The first group consists of the furniture that was made in the mid-thirties of the twentieth century according to the plan of Nikola Krasnov. It makes a unique entirety with other elements of the interior. The second group is furniture that had gradually been replacing the original furniture during the second half of the twentieth century. Today it is the basis of the interior of the parliamentary premises. Parts of the original furniture are scattered all around the building.

On the basis of the preserved furniture, created between 1935-1938, we can draw the conclusion that special attention was given to the quality of used material. The furniture was made of first-class Slavonian oak and walnut wood and upholstered with carefully chosen leather in red, green, blue and brown. Woodwork and upholstery were performed by the best craftsmen in the period between the two wars.

The furniture adds to the importance and representative characteristic of the building. Depending on the importance of particular rooms, the degree of applied decorative elements varies, but the quality of processing remains even. The main decorative technique used for ornamenting the furniture was engraving. The decorative elements of different historical styles were combined, including renaissance, baroque, rococo and ampira, and the influence of art deco the prevailing style at the time, is noted in the design of certain objects.

The central hall, diplomatic salon and library are the only premises in the parliamentary edifice in which the original arrangement of furniture was kept, according to the design of Nikola Krasnov. In the big and small plenary halls, there are original benches and tables for deputies. The furniture for the Assembly Chairperson's office and the Support Service offices is one of the most beautiful style entireties, which remind one a great deal of the original display.

The style of the furniture from the second half of the 20th century varies. The monumental and representative characteristics of the furniture between the two wars are observed. From that period the two conference tables from the committee halls stand out especially. They completely follow the original style of Krasnov's designs and fit perfectly into the interior of these premises, with the well-combined decorative elements of doorposts and plaster decorations.

Designing the furniture for this edifice, the architect Nikola Krasnov expressed all his knowledge and experience, offering customers the interior in accordance with the importance of this state institution.

The lights, as well as other interior elements, whose author is Nikola Krasnov, are designed especially for this representative edifice.

Arranged on all levels, depending on the purpose of the space, they are more or less luxurious. With their ornamental appearance, they fit the style of the entire interior atmosphere. They were put in place in 1936, with some exceptions, and up to now, over 600 original lights have been preserved. They can be divided into four groups: chandeliers, ceiling fixtures, wall sconces and candelabras. They are all made of bronze or brass with adequate glass parts.

The most representative among the light fixtures is a chandelier in the diplomatic salon, which belongs to the group of huge gilded bronze chandeliers with 36 candles.

In both presidential offices, there is the same type of luxurious chandelier, which emphasizes the importance of these premises. The candelabras in the vestibule stand out with their perfect proportions, contributing to the overall impression of the representative characteristic of the parliamentary edifice.