She and her late son's three children brought the suit against AEG Live, the company that was promoting the singer's ill-fated comeback tour. It would be her first court appearance in the case.
Katherine Jackson, 83, and her grandchildren -- Prince, Paris and Blanket -- claim the entertainment giant negligently hired and controlled the physician who gave the singer a fatal dose of the anesthetic propofol in 2009, days before his "This Is It" tour was to open in London.
AEG says it was Jackson who hired Dr. Conrad Murray, and that any money the company was supposed to pay the doctor was an advance to the singer.
Murray is serving jail time for his involuntary manslaughter conviction.
Katherine Jackson is not the first family member to testify in the months-long trial, but the family matriarch may be among the most anticipated witnesses.
Michael Jackson's eldest son, Prince, took the stand in late June, when the 16-year-old testified about his childhood, his father's preparations for the "This Is It" tour, and the day the singer died.
Two of Michael Jackson's nephews have also testified, including TJ Jackson, who with his grandmother shares guardianship over the King of Pop's children.
Katherine Jackson has spent much of the trial seated in the front row of the courtroom, where she has been well-received by her son's fans who also routinely watch the proceedings.
On a recent day, some of the fans lined the hallway as Katherine Jackson walked to the elevator, flanked by her nephew, Trent, and security.
The fans waved as the matriarch moved slowly past.
"We love you. We love Michael so much," they said, blowing kisses.
She lifted her hand to wave before leaving.