Angry onlookers in the resort island of Samui jeered as Umaporn Sarasat, 43, knelt before a picture of the late Thai king.
The small business owner has been accused of insulting the monarchy, after allegedly posting a disrespectful comment about the country's late King Bhumibol Adulyadej.
A line of police officers linked arms to keep the crowd from surging forward.
The country is observing a one year mourning period following the late king's unprecedented 70-year reign.
Ms Sarasat is one of three accused of 'Lese Majeste' - insulting the monarchy, a charge which carries a maximum jail term of 15 years.
A crowd publicly shame Umaporn Sarasat as she arrives at a police station to face charges of insulting the monarchy (AAP) Source: AAP
"We are going to proceed with the case as best we can," district police chief Thewes Pleumsud told the crowd.
"I understand your feelings. You came here out of loyalty to his Majesty. Don't worry, I give you my word."
Authorities in the country of more than 67 million people are urging calm after swarms of people took to social media to criticise those who aren't wearing black and white clothing to mourn the late monarch.
A government spokesman said some Thais can't afford mourning clothes and urged tolerance, as there are reports of price gouging as demand for such clothing has surged.
-With AAP
