She travelled to Patong Beach on the island of Phuket, after making a one-match comeback in a tournament in Pattaya, and met street children being cared for by a charity organisation.
After seeing the work being done to restore shops and restaurants along the beach road, she visited the Patong Municipality School and was greeted by around 50 children who had lost their parents in the tsunami.
When one small child came up and took her hand, it was too much for the Swiss woman to bear.
"Seeing the kids who have lost so much is what really stands out from my week in Thailand," Hingis told reporters.
"But also seeing the things which were destroyed - the streets and the beach, and the atmosphere. It's so quiet.
"You really want people to come back, but it would be better if people were able to come and help somehow instead of just sitting on the beach. That would feel strange to me."
Hingis, a goodwill ambassador for the World Health Organisation, agreed last year to play in Pattaya to raise funds for organisations looking after women and children who suffered abuse and deprivation.
The 24-year-old, winner of five grand slam singles titles, retired in late 2002 because of injury.
