The technology of the Swiffer Mop is credited to the Research and Design Network at KOA Japan. However, Procter & Gamble maintains that its Swiffer Mop was invented within the company and hit the market in 1999. No single individual is given credit for the mop's invention, however.
As is the case in most large companies, Procter & Gamble has teams of people working on projects, and the Swiffer seems to be no exception. A Kinesis article points out that the well-qualified team set out to develop a stronger cleaner and, through observation, came up with what would become this billion-dollar product line.