Global investors are betting on America's economic success now more than ever, Morgan Stanley's Ruchir Sharma told CNBC on Monday.

"This year has been a story of how well America has done," he said on "Squawk Box," calling it an example of "American exceptionalism."

"We may or may not believe in [American exceptionalism], but the financial markets have never believed in it to such an extent," added Sharma, head of emerging markets and chief global strategist at Morgan Stanley Investment Management. The global firm has $474 billion in assets under management, as of June 30, 2018.

The strong economy has been touted by Trump administration officials such as top aide Larry Kudlow, who called it "the hottest economy in the world."

Second-quarter gross domestic product gained 4.2 percent, according to the government's final reading. And it appears the momentum has continued. The Atlanta Fed's GDPNow real-time indicator put the third-quarter growth at 4.1 percent, as of Monday.

Combine those figures with the first quarter's 2.2 percent gain, and the economy stands to grow at an average of 3.5 percent for the first nine months of 2018.

Sharma said that excellent economic performance is reflected in the "very richly valued" U.S. financial markets.

In fact, the stock market has doubled over the last decade, leaving a "huge gap" compared with international markets, particularly emerging ones, he added.

The is up 7.65 percent this year. Meanwhile, the iShares MSCI Emerging Markets ETF (EEM) dropped just over 13 percent in the same period.

However, the U.S. stock market hit a snag over the last three trading sessions, selling off after a jump in interest rates. That's led some prominent market watchers, like Wharton's Jeremy Siegel, to predict a difficult time for equities in the coming months.

— CNBC's Matthew Belvedere and Jeff Cox contributed to this report.