Republican lawmakers, meanwhile, have requested a detailed accounting of public money spent on the expedition.
"You can't really be effective as a governor in a global economy … unless you are engaged abroad and doing things that only the governor's office can do," the Democratic governor told reporters in Annapolis.
The Asia was O'Malley's first to the world's fastest-growing region. Other governors, including Robert L. Ehrlich Jr., his Republican predecessor, made similar expeditions.
What distinguished O'Malley's trip was the size. Nearly 70 officials, educators and business leaders, who paid their own way, accompanied O'Malley for at least part of the mission.
While O'Malley was overseas, the Maryland House Republican leadership wrote to the state Department of Business and Economic Development asking for a breakdown of state expenses.
"Could the same thing have been accomplished without such a large delegation traveling on the taxpayer's dime?" House Minority Leader Anthony O'Donnell asked.
A spokeswoman for DBED, which organized the trip, said tax dollars were used to fund travel for six officials. That does not include O'Malley's security detail or University System of Maryland staff.
A more complete accounting is expected later this week.
O'Malley, who had never traveled in Asia, said he was struck by the "enormity" of the sprawling Asian cities and the "the pace of the industrial progress." He noted that Shanghai, one of the five cities he visited, has a population 35 times that of Baltimore.
The pace of development was also stunning, he said. On a high-speed train ride from Shanghai to nearby Nanjing he said he "saw nothing by cranes on the horizon."
He spoke also of a downside to the rapid development and industrialization. In five days in China, he said, "we never saw the sun. We never saw the sky. So thick was the smog."
Lin Hwang, vice president of J&R Seafood Inc. in Cambridge, said the trip was "better than expected."
Hwang's company exports blue crabs to South Korea. He met with five potential buyers in China, where he said drought has made crabs scarce; he said one wanted an exclusive deal "for everything we could produce."
Terry Lin, the chief executive officer of Planned Systems International in Columbia, said the trip accelerated the pace of a $45 million deal the information technology consulting firm had been negotiating with a Chinese company. The contract was one of the first O'Malley announced during his trip.
The governor hinted that more deals from the trip are in the works.
The governor displayed a slideshow of pictures from the trip, including images from the Great Wall of China and The Forbidden City in Beijing. His 13-year-old son William joined him during those portions of the trip, at O'Malley's expense.
O'Malley was also photographed visiting the Demilitarized Zone between North and South Korea. The image shows him standing inside a building on the border as two North Korean soldiers outside glare through a window over his shoulder.