The bB was a compact car that mounted a multi-purpose vehicle (MPV) body on the platform of the Vitz. The name bB was derived from the initials for "black box." It was popular among young Americans at the time to modify and personalize their vans, and it was this trend that inspired the styling of the bB. The vehicle was fully digitally designed, using computer graphics-based virtual models without building a single physical prototype. The Honda S-MX had been enjoying popularity among Japanese youths since its debut in 1995, and the entry of the bB further expanded the market for this type of vehicle. Although the bB was originally aimed at young generations, it proved popular across wider age groups due to its usefulness and ease of handling.

In June 2001, an open deck version was added to the line, removing the top of the rear cabin. The hatch gate and the hatch window that divided the deck and the cabin could be opened up to enlarge the integrated cabin-deck space. The rear door on the left was rear-hinged, offering wide access to the interior when both the front and rear doors on the left were opened, as the center pillar was integrated with the doors.