The inauguration of Zachary Taylor as the 12th president of the United States was held on Monday, March 5, 1849, at the East Portico of the United States Capitol in Washington, D.C., and was the second instance of an inauguration being rescheduled due to March 4 falling on a Sunday, the Christian sabbath. This was the 16th regular inauguration and marked the commencement of the only four-year term of both Zachary Taylor as president and Millard Fillmore as vice president. Taylor died 1 year, 126 days into this term, and Fillmore succeeded to the presidency. The presidential oath of office was administered by Chief Justice Roger B. Taney. Inauguration Day started off being cloudy with snow flurries, but turned to heavy snow during the inaugural balls.

The oath of office of the president of the United States is the oath or affirmation that the president of the United States takes upon assuming office. The wording of the oath is specified in Article II, Section One, Clause 8, of the United States Constitution, and a new president must take it before exercising or carrying out any official powers or duties.