The Byzantine Empire did not have one single, formally codified symbol in the modern sense. Instead, it was represented through a broader set of imperial insignia used to signal authority, legitimacy, and continuity of rule.
Among those imperial icons, the double-headed eagle is the emblem most widely linked with Byzantium. It became the most prominent and enduring image associated with the empire, which is why many readers searching for the Byzantine Empire symbol are directed to that design first.
The key point in this explanation is that Byzantium was identified by a collection of symbols rather than one exclusive badge. That makes the answer slightly more complex than a simple logo or coat of arms, because imperial identity was expressed through multiple ceremonial and political markers.
For people asking what the symbol for the Byzantine Empire was, the clearest short answer is the double-headed eagle. A fuller answer is that this eagle stood out within a wider tradition of Byzantine imperial insignia, making it the de facto symbol most strongly associated with the empire today.