The London-listed company, which has been fending off a hostile takeover bid from Canada's GardaWorld, said it has retained and won contracts with an annual revenue contract value of 2 billion pounds ($2.58 billion) for the nine months ended Sept. 30.
G4S, one of the world's largest private-security firms employing more than half a million people in 90 countries, said revenue for the period remained resilient.
"Group revenue was just 2% lower overall, and this was more than offset by tight direct and indirect cost control and reduced interest costs, with the latter reflecting both refinancing benefits and the improving net debt position," the company said in a statement.
The British company sold most of its cash-handling operations in February to U.S. peer Brinks Co to focus on its security business.
The firm earlier said it expected to save 100 million pounds in 2020 from productivity gains and restructuring.
G4S, which is now at the centre of a bidding war, said in July that it expected increased demand for thermal cameras and screening personnel as businesses reopen after many countries eased lockdowns.
The security contractor, after a series of setbacks in recent years, rejected GardaWorld's hostile bid last month. A second potential suitor, U.S. rival Allied Universal, expressed interest last week, signalling that consolidation in the industry was gathering pace.
(Reporting by Aakash Jagadeesh Babu and Pushkala Aripaka in Bengaluru, Editing by Sherry Jacob-Phillips)