Amazon employees are pictured outside the Amazon Go brick-and-mortar grocery store in Seattle, Washington on December 5, 2016.

Amazon has become a major player in the search engine space, and could soon become a "more important search engine than Google," NYU Stern School of Business professor Scott Galloway told CNBC on Tuesday.

As Amazon reinvents the very industry it disrupted, retail, it is also becoming a primary shopping search engine for consumers, with 55 percent of searches beginning on the site.

Galloway says "Amazon is becoming all of retail" and that consistent innovation has made it "the most disruptive company in the largest economy in the world" — and that disruption fully justifies its lofty valuation. Eventually, people will only shop at Amazon, he said.

"The upgrade of Amazon stock today has nothing to do with selling goods. It's about sponsored goods on the site," said Galloway. That could lead to continued growth in the company's ad business, which Galloway says would "put them in the league of Facebook and Google."