Thousands of supporters wearing T-shirts bearing Megrahi's picture threw petals and waved Scotland and Libyan flags as Megrahi alighted the aircraft with the Libyan leader Muammar Gaddafi's son Saif.
Megrahi, who is suffering from prostate cancer was set free on compassionate grounds.
However, on Thursday, Aug 20 the US President had condemned Megrahi's release as a mistake. He added that US had requested the Libyan government to keep Megrahi under house arrest till death.
"We have been in contact with the Scottish government, indicating that we objected to this," Obama said. "We thought it was a mistake."
Even on the last day in prison Megrahi, who was convicted for bombing the Pan Am flight 103 denied his guilt.
He has left an appeal against conviction to facilitate his release.
"The interests of justice have not been served by this decision," said Eric Holder, the US attorney general, who had initially investigated. "There is simply no justification for releasing this convicted terrorist whose actions took the lives of 270 individuals."
However, Macaskill, the Scottish justice secretary and former criminal defence lawyer said the decision was a moral act.
"In Scotland, we are a people who pride ourselves on our humanity. It is viewed as a defining characteristic," he said.