Official ceremonies were scheduled in the capital Stockholm and in the southern cities of Gothenberg and Malmö.
Hundreds of Swedes also took part in an emotional beachside ceremony in the Thai resort of Khao Lak that included flowers, incense and music.
The beachside commemoration, held as the sun broke through a passing rainstorm, drew hundreds of people at a resort and was broadcast live on Swedish television.
Bishop Lennart Koskinen presided over the ceremony and remembered an earlier trip to Thailand with grieving families, when Swedes and Thais set flowers at the beach.
“Their flowers mingled with ours. We walked together, and I felt a unity with everyone,” he said. “We felt like common people. We were all united in our sorrow.”
Most of the 90-minute service was filled with music, mostly songs in Swedish but also an English-language hit by 1970s Swedish pop group ABBA, “I Have a Dream”.
After the service, dozens of families took off their shoes and waded fully clothed into the sea, where they released traditional Thai offerings to the dead.
The offerings, known as krathongs – small floats made from banana leaves carrying incense, candles and flowers – drifted away as other families left their own offerings on the beach.
Under one tree, families set flowers and teddy bears beneath pictures of children who died in the killer waves. Others set small shrines of flowers and candles in the sand, alongside cards bearing the names of the dead.
Anne Gustafson said she had come to the service because she couldn’t stand to spend Christmas in Sweden after her sister, brother-in-law and one of their children died in the tsunami.
Since then, she has raised her sister’s surviving son, nine-year-old Philip, who also came to the service.
“He doesn’t say much. It’s difficult because we don’t know how he feels,” she said.
During their visit, she said Philip recognized many of the places he saw during the tsunami, and had met with some of the rescuers and other people who had helped him during the aftermath.
As many as 20,000 Swedes were vacationing in Southeast Asia at the time of the tsunami on December 26, 2004, most of them in Thailand. More than 220,000 people were killed and the lives of millions more were altered forever by the tsunami, unleashed by one of the world’s largest-ever earthquakes which struck off the Indonesian island of Sumatra.
In Sweden, a minute’s silence was observed and 543 candles – one for every Swedish person dead or missing – lit during each of the ceremonies, according to a program by a Swedish assocation for people affected by the disaster.
The ceremonies included music and songs as well as speeches by Swedish officials, survivors of the disaster and friends and family members of those who died.
In Stockholm, King Carl XVI Gustaf, Queen Silvia, Crown Princess Victoria and Prime Minister Göran Persson participated in an event in the snow at Skansen, an open-air museum on one of the capital’s hundreds of islands.
Foreign Minister Leila Freivalds said on Saturday that she would not attend as “my presence has sparked reactions” from the survivors and the families of those who died.
Sweden’s government has over the past year been repeatedly criticized for its slow and lacklustre response to the tragedy, with little communication and assistance available to thousands of Swedish survivors.
Early this month, a government-appointed commission into the tsunami issued a scathing report that charged the government “lacked organization to handle serious crises.”
An exhibit was also scheduled to open in Stockholm Monday at the Museum of Far Eastern Antiquities entitled “After the Tsunami”, in which Swedish and Asian children who survived the tragedy recount their harrowing ordeals.