Cobbold, who has worked at Chloride since 2007 and formerly worked at Smiths Group, had been in advanced talks with De La Rue over the past month and starts his new job in January.
Investors have craved resolution to De La Rue's leadership hiatus since former chief executive James Hussey stepped down after the company reported serious failings at a paper factory, leading to profit warnings and a slump in its shares.
"(Cobbold's) wealth of experience, including of international business at the most senior level, will be invaluable to De La Rue both in the short term as we work to resolve current uncertainties," De La Rue's non-executive Chairman Nicholas Brookes said.
Last week De La Rue rejected a takeover approach worth £895m ($1.4 billion) from French rival Oberthur Technologies, calling it "highly opportunistic".
Hussey was highly regarded for his strong network of international and diplomatic contacts, which were seen by analysts as a major advantage in a secretive business which depends on government clients.
De La Rue's shares had shed more than 35 per cent, before regaining some of their value when they rallied 30 per cent on news of Oberthur's bid. Shares last traded at 834.5 pence each, valuing the company at around £825m.