"This award puts us much above all the competition in Shanghai," said Ritz-Carlton regional vice-president, Asia Pacific, Mark DeCocins.
He added that the Shanghai property would now be a benchmark for all the other Ritz properties in China.
He said: "All of them will aim for the same standard. But with this honour also comes the pressure of keeping it up."
Michelle Wan, director of communications, said the award enhanced the hotel's reputation, especially within the domestic market. "We have been receiving more enquiries," she said.
The Portman Ritz-Carlton, which opened in January 1998, was invited to apply for the ranking in 2005.
The hotel was officially nominated in May 2006 and finally awarded the rating in August this year.
There are currently close to 300 five-star hotels in China. The other hotels in the inaugural batch of recipients are the China World Hotel in Beijing and Garden Hotel in Guangzhou.
To qualify for the platinum five-star rating, a hotel must have been in operation, and retained its five-star rating, for more than two years.
Other considerations were location, architecture and decor.
