It is the latest move in its ongoing restructuring work, and comes two weeks after the firm said it was closing its loss-making workwear and linen units.
In a brief statement, Rentokil called its Manned Guarding arm a "high-quality business". The unit offers security, CCTV operations and mobile patrols.
Rival security firms and private equity groups are believed to be interested.
Rentokil, which also offers pest control and hygiene services, is continuing efforts to turn around its fortunes.
Back in November, it sold off its 29 UK conference centres to private investors for £325m ($567m).
Source: BBC