The Rockwell B-1B is again a unique aircraft. It is a sleek, dartlike aircraft with "swing wing" capability. Its wings can be extended to full span for take-off, landing, and long-range cruise while in swept back position it allows for high-speed penetration of adversary airspace. Although the swing wing capability does impose a weight penalty, it enables the aircraft to use shorter airstrips. Minimum sweep is 15 degrees and maximum sweep is 67.5 degrees. In order to ensure aerodynamic cleanliness, the junction where the wing sweeps into the wing glove features a so-called seal. The sealing system was derived form that developed for the European swing-wing Panavia Tornado strike fighter, and features an inflatable bag covered with "fingers". Furthermore, the wing has lift-enhancement devices for relatively short take-offs with a full load, including seven-segment full-span leading-edge slats and six-segment trailing-edge Fowler-type flaps. Lateral control is provided by four spoilers on top of each wing which are used for airbraking as well.

The Rockwell B-1 is configured with a conventional tail configuration, with an all-moving horizontal tailplane and a single tailfin. Moreover, the rudder has three sections with the horizontal tailplanes can move in opposite directions to help with lateral control. By turning them to their maximum nose-down position, the horizontal tailplanes act as an airbrake on landings.

The B-1 Lancer is fitted with eight self-sealing fuel tanks, which fill up much of the fuselage and parts of the wing assembly. If necessary, additional fuel tanks can be installed in the weapons bay. All fuel tanks are pressurized with inert nitrogen to reduce fuel explosion hazard. The B-1B's FCGMS (Fuel & Center Of Gravity Management Subsystem) shifts fuel from one tank to another in order to maintain trim when the aircraft changes the sweep of its wings.

Just like many other long-range combat aircraft, the B-1B is fitted with a midair refueling socket in the nose, just forward of the wingshield. The position of the socket allows the B-1 bomber's flight crew to keep an eye on the tanker's refueling boom. Moreover, the B-1B is made mostly of aluminum alloys and titanium, with some composite elements. For example, the box supporting the swing wing structure is made entirely of titanium. Furthermore, the aircraft is structurally reinforced in order to withstand the shock of a nuclear blast. The B-1B's fuselage has smooth contours, increasing aerodynamic performance, and uses radar absorbing material (RAM) in order to give it a radar cross section only about one or two percent of that of the B-52, despite the fact that the two different aircraft are roughly the same size.

As said, the B-1B is powered by four General Electric F101-GE-102 afterburning turbofan engines, with each having 17,000 lb of thrust and 30,780 lb of thrust with afterburning. If necessary, the B-1B can fly on only two engines, and can even fly on one if fuel is dumped. Cabin pressurization is distributed throughout the aircraft and is provided by engine bleed. Besides its four engines, the aircraft is fitted with an APU mounted between the engines in each pod, and are used primarily to start the engines and provide ground power. The APUs allow a quick startup of the engines in order to enable it get of the runway very quickly. Switches on the nosewheel gear allow a ground crew man to start the APUs and engines as the crew boards the aircraft. Compared to the B-1A, the B-1B has fixed engine inlets which cuts its speed at high-altitude to Mach 1.25.