From the guest list to Covid-19 changes, to new security concerns, here's everything you need to know about the big day.
The inauguration is the formal ceremony that marks the start of a new presidency, and it takes place in Washington DC.
The only required feature is that the president-elect recite the presidential oath of office: "I do solemnly swear that I will faithfully execute the Office of President of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States."
Once he utters these words, Biden will then take his place as the 46th president and the inauguration will be complete (but that's not all - celebrations follow).
Kamala Harris will become vice-president once she takes the oath of office, which usually happens just before the president is sworn in.