In one of the most emotional moments in the 25-year history of her daytime show, Miss Winfrey introduced her own long lost sibling in what she called a “miracle of miracles.”

The half-sister, called Patricia, was born in Milwaukee in 1963 and given up for adoption by Miss Winfrey’s mother Vernita Lee. The multi-millionaire media mogul only discovered her existence at the end of October.

When Patricia, whose last name was not disclosed, was born Miss Winfrey was aged nine and living with her father in Nashville, Tennessee. She never knew that her mother was pregnant and had given birth.

Miss Winfrey, close to tears, said: “Yes, it is true that my mother Vernita is also Patricia’s birth mother. That means Patricia is my half-sister.”

Miss Winfrey had two other siblings, a brother and a sister, but both are deceased. She said the discovery of another sibling had left her, for once, “speechless.” She said: “For the most part, my life has been an open book and on the show I think I’ve seen about everything, and I thought nothing could surprise me anymore, but let me tell you I was wrong.”

The family link was discovered by Patricia, a single mother of two who was raised in foster homes from the age of seven. She began looking for her birth mother in 2007 and established that it was Vernita Lee.

She set about contacting her lost family but only succeeded after repeated attempts.

Miss Winfrey was told of the development by a relative just as she was about to go on air.

The chat show presenter then called her mother, who confirmed the truth, and the two women were reunited in an emotional meeting at their mother’s home on Thanksgiving Day in November.