Ms Yingluck was seen shopping at Tesco Lotus, Ram Intra branch, on Pradimanootham Road before noon.
Shoppers took the opportunity to snap photos of the former premier in her first public appearance since returning from a trip to Europe and the USA on Sunday night.
Ms Yingluck told reporters that she would not need to report to the National Council for Peace and Order as she had returned Thailand by the date earlier approved.
She admitted that some people might have questioned whether she would return, but the trip was primarliy for her to spend time with her son before his school term began.
“I thank the people who were worried about me. Personally, I have no intention to leave Thailand,” she told reporters.
Ms Yingluck left Thailand for a holiday in Europe and the United States after she was granted permission to leave the country between July 23 and Aug 10. She was required to request permission because of pending legal allegations against her.
A few days before her scheduled return date, rumour monger planted stories that Ms Yingluck had written to junta chief Prayuth Chan-ocha asking for extra time abroad, until the end of the month.
Lt Gen Kampanat Ruddit, director of the NCPO’s Centre for Reconciliation and Reform, said the reports were unfounded. Ms Yingluck had not made any such request and her schedule remained unchanged.
During her overseas trip, Ms Yingluck attended the 65th birthday celebrations on July 26 for her brother Thaksin in Paris. Speculation was rife that she might stay abroad rather than return to face charges of dereliction of duty in connection with her government's failed rice-pledging programme, and other allegations.