Alongside Marriott, the Spanish clothing giant Zara, Delta Air Lines and Medtronic - a medical device company - were all called out by Chinese authorities for "illegal" classification of regions that Beijing claims under its authority.
The Civil Aviation Administration of China (CAAC) has demanded an "immediate and public" apology from Delta Air Lines for listing Tibet and Taiwan as countries on its website.
Officials said Marriott had "seriously violated national laws and hurt the feelings of the Chinese people".
The CAAC said on 12 January that it had asked the airline to investigate the incident, reports Reuters; until Friday morning it was possible for customers visiting Delta's complaint and comment section on its Chinese website to select Tibet and Taiwan as their country of origin.
In a statement, Delta apologised for making "an inadvertent error with no business or political intention", saying it recognised the seriousness of the issue and had taken steps to resolve it.
On Weibo, the Chinese social media platform, Marriott said, "we will absolutely not support any separatist organization that will undermine China's sovereignty and territorial integrity", The New York Times reported.More news: Fox announces changes to its X-Men movie slate
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"We apologise profoundly for any behaviour that will cause misunderstanding about the above stance".
Previously, a Chinese internet user had posted a screen shot of Marriotts questionnaire, which listed Tibet, Hong Kong, Macao and Taiwan as options under the question "Which country are you from?" The administration said tourist accommodation is a core factor of a country's tourism industry.
Tibet is officially an "autonomous region" but firmly under Chinese control.
However, netizens believe the apology lacks sincerity, as the company's official Twitter account then went on to "like" a Tibetan independence-related post on Twitter (see below). China claims Taiwan - an independent, democratically-run island - as a renegade region to be reunified with the mainland in the not-too-distant future.
"Marriott International respects and supports the sovereignty and territorial integrity of China".
Upon completion of a full investigation into how both incidents happened, we will be taking the necessary disciplinary action with respect to the individuals involved, which could include termination, changing our approval and review procedures for online content, reviewing our customer feedback channels, and enhancing training to ensure these situations don't happen again.