"The United States is joining the international community in this effort because of our belief that immediate action is required to avert a humanitarian and human rights catastrophe in the Central African Republic, and because of our interest in peace and security in the region," Defense Secretary Chuck Hagel spokesman Carl Woog said in a statement.
The United Nations warned last month the landlocked nation of 4.6 million people was at risk of spiraling into genocide and France described its former colony as "on the verge of genocide."
Boeing C-17 Globemaster III military transport aircraft will carry hundreds of African Union troops from Burundi to the Central African Republic, where France has deployed 1,600 troops since Saturday to try to quell the violence, the Defense Department said.
France is operating under a U.N. Security Council resolution.
More than 2,500 African Union troops are in the Central African Republic. That number is expected to be increased to 3,600 by January.
The Obama administration pledged $40 million to support the African Union forces Nov. 20.
The U.S. deployment, expected to start with multiple flights by Wednesday, will involve U.S. pilots and aircrews but no U.S. ground troops, Defense Department officials said.
But the department is exploring possible additional U.S. resources that could "address further requests for assistance to support the international community's efforts," Woog said.
The Central African Republic descended into violence in March when a rebel group called the Seleka rebel alliance, made up mostly of Muslim fighters, many of them from neighboring Chad and Sudan, conquered the capital, Bangui, and overthrew President Francois Bozize.
Seleka leader Michel Djotodia named himself president March 24.
Muslim-Christian fighting since then has brought the nation "into complete chaos," U.N. Deputy Secretary-General Jan Eliasson said.
More than 400 people were reported killed in two days of violence last week, but it is difficult to know how many people have really been killed in the conflict so far because it is too dangerous to go t the rural areas where most killings occur, a U.N. spokeswoman told the BBC.
Christians make up half of the country's population and Muslims 15 percent, the CIA World Factbook says.