This paper aims to introduce the framing system in Byzantine monumental painting and describe its elements and functions. First, the nature of the Byzantine framing system has been explained, and the different framing elements that form the system have been defined. The subject has been discussed through selected examples from early to late period Byzantine art history. The main principles of the Byzantine framing system have also been briefly examined in relationship to architecture, painting programs, and frames. Moreover, the paper indicates the different framing practices, and reasons for them, between mosaic and fresco decorations and the relationship between the ornament and the frame. In conclusion, it can be argued that framing in monumental painting was a multilayered and multifunctioning system, formed by several intertwined frame layers. In the multilayered framing order, while each representation has its own autonomy with its frame, framing integrates the overall program through different frame layers as well. In this paper, we show the different framing modes between mosaic and fresco reflect the difference in surface characteristics, and how an ornament can be seen as a means of improving the functions of framing.