Company founder Jack Ma was on the floor of the New York Stock Exchange as trading opened, while a group of Alibaba customers rang the opening bell.
A trading price was not available in the early minutes after the opening, which is not uncommon for stock market debuts.
By raising as much as USD 25 billion, Chinese online giant Alibaba is poised to break the record for the largest initial public offering in history.
Speaking to CNBC television from the trading floor, Ma said he was "very honored, and so excited" by the market debut and that he sees enormous growth potential for Alibaba.
"We have a dream," he said. "We hope in the next 15 years the world will change. We want to be bigger than Wal-Mart."
He added that he sees Alibaba as a company that will have a huge impact: "We hope people say in 15 (years) this is a company like Microsoft, like IBM.