The Chesapeake Bay Bridge–Tunnel (CBBT, officially the Lucius J. Kellam Jr. Bridge–Tunnel) is a 17.6-mile (28.3 km) bridge–tunnel that crosses the mouth of the Chesapeake Bay between Delmarva and Hampton Roads in the U.S. commonwealth of Virginia. It opened in 1964, replacing ferries that had operated since the 1930s. A major project to dualize its bridges was completed in 1999, and in 2017 a similar project was started to dualize one of its tunnels.

With 12 miles (19 km) of bridges and two one-mile-long (1.6 km) tunnels, the CBBT is one of only 14 bridge–tunnel systems in the world and one of three in both Hampton Roads and the United States. It carries US 13, which saves motorists roughly 95 miles (153 km) and 1+1⁄2 hours on trips between Hampton Roads and the Delaware Valley and points north compared with other routes through the Washington–Baltimore Metropolitan Area. As of January 2021, over 140 million vehicles have crossed the CBBT.

The CBBT was built and is operated by the Chesapeake Bay Bridge and Tunnel District, a political subdivision of the Commonwealth of Virginia governed by the Chesapeake Bay Bridge and Tunnel Commission in cooperation with the Virginia Department of Transportation. Its construction was financed by toll revenue bonds, while operating and maintenance expenses are recovered through tolls. In 2002, a Joint Legislative Audit and Review Commission (JLARC) study commissioned by the Virginia General Assembly concluded that "given the inability of the state to fund future capital requirements of the CBBT, the District and Commission should be retained to operate and maintain the Bridge–Tunnel as a toll facility in perpetuity".

The tunnel sections addressed concerns that a bridge failure across critical shipping lanes would block not only shipping but navy access.

A similarly named Chesapeake Bay Bridge crosses the Chesapeake Bay farther north in Maryland connecting Annapolis and Kent Island.