An independent Scotland could take marketing lessons from Singapore's business-friendly, trade-dependent economy, the world's largest advertising group told CNBC.

"From a sort of marketing, trade and investment point of view, I think [an independent Scotland] would mirror Singapore," Sir Martin Sorrell, CEO of WPP (London Stock Exchange: WPP-GB), told CNBC on Thursday.

The Southeast Asian city-state is consistently ranked one of the world's easiest places to do business. It's also the city with the best investment potential globally, according to the 2014 Business Environment Risk Intelligence (BERI) report.

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Cutting the corporate tax rate to attract companies and compete with Ireland's tax-haven image is a key pillar of the 'Yes' campaign, the organization behind the separatist movement.

In late August, more than 200 business leaders signed a letter stating their support for the campaign, saying that "an independent Scotland will recognize entrepreneurs small and large as the real wealth and job creators of the nation's economic future." The country already enjoys a high level of foreign direct investment (FDI). In June, Ernst & Young said FDI stood at a sixteen-year high, with the U.S. accounting for nearly 40 percent.

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"You know, the Chinese I'm sure will be interested in investing in Scotland. Maybe even other countries too," Sorrel remarked.

It remains to be seen whether China, which faces its own issues with regional separatist movements in areas like Tibet and Xinjinag, will embrace the opportunity. During a press conference with U.K. leader David Cameron in June, Premier Li Keqiang said he wanted a "united United Kingdom.

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Wealthy property buyers from China, Taiwan and Singapore flocked to Edinburg in recent years, triggered by the rising number of international students in Scottish universities. A 2014 report from real estate firm Savills (London Stock Exchange: SVS-GB)showed the number of Chinese students spiked 78 percent over the last five years.

A new face of foreign relations

With less than a week left until the September 18 vote, questions about how an independent Scotland would fare in the global economy are flying.

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"I think the very interesting thing that [the referendum] raises [is] what are Scottish foreign relations going to look like?" Sorrell asked. "Who is the lender of last resort? Will the Bank of England still be the lender of last resort? Will there be an equivalent in Scotland? I mean it is a very complex situation," he said.