"It's my honour to be here with you," the First Lady told the victims' families when she met them in private, away from the media glare, at Oak Creek High School.
"I'm sorry it's under these circumstances, but I am anxious to meet with the families and lend whatever support I can," she said. She spent about 30 minutes with the Sikh families.
In addition, the family of police officer Lt. Brian Murphy, who was shot more than eight times by white supremacist Wade Michael Page on Aug 5, met her in a separate room.
40-year-old former US Army specialist Page went on a rampage, killing six Sikh worshippers and wounding three.
After her visit, the Sikh community said in a statement that Michelle had "brought comfort and assurance during a period that has been marked with tremendous sorrow and grief."
They told her visit goes a long way to assuage the feelings of hundreds of Sikh families across the nation.
Gurdwara secretary Kulwant Singh Dhaliwal and Oak Creek Mayor Stephen Scaffidi greeted a sombre first lady in a hallway of the school, where more than 3,000 mourners turned out this month for funeral of the six Sikhs.
"It is very nice of you to come and share our grief. This means a lot to all of us and helps the situation. We truly appreciate you to take time to visit all the affected families and convey your condolences and feelings," Dhaliwal said.
"First lady was very gracious. She told me that 'please let me know if I can do anything to help'," he said. Families began to line up in the hallway outside the gymnasium about 20 minutes before Michelle's visit.
Later, Michelle spoke at a campaign event and the crowd at Bradley Tech applauded other members of the Sikh community when they walked into the rally.