Since Sigillum Multarum was created in 2020, there have been two logos used by the series.

Current Flag (2022-present)

The current flag of Sigillum Multarum consists of 6 black-and-white stripes with the flag of Hand-in-Shot Productions on it. The colors of purple, black, and white are derived from the logo of the company, while the pattern is based on the flag of the United States, where the series comes from. Meanwhile, the five principles of vexillology are written on 5 of the stripes, and Sigillum Multarum is written on the 6th. This flag was introduced to commemorate the 20th episode of Sigillum Multarum.

Former Flag of Sigillum Multarum (2020-2022)

This was used as the logo of the series from its beginning in 2020 until 2022, when it was replaced in time for the 20th episode of Sigillum Multarum.