"Growth is there, but it's in limited sectors of the economy despite what the stock market is saying," Sorrell told CNBC's "Squawk Box" on Thursday.
The advertising guru said most growth is coming from technology with the "Fearsome Five" of Google, Apple, Microsoft, Amazon and Facebook dominating. Meanwhile, in the U.S. pharmaceutical industry, contract manufacturing organizations are also posting rapid growth, he added.
Sorrell said WPP is investing in more digital services, and Facebook and Google will be the top two destinations to which the firm directs media spending this year.
As for Chinese tech companies, they are also establishing global import as they already dominate the market in the world's second-largest economy, he said, pointing to the "BAT" trio of Baidu, Alibaba and Tencent.
"We in the West tended to think China copied technology, or even stole technology. If that was the case, that's no longer the case," he said.