Thomas Markle, 81, underwent a three-hour operation to remove his left foot and lower leg earlier this week, after the limb went black as a blood clot stopped blood circulation.
Although Meghan has been estranged from her father - a retired TV lighting director who now lives in the Philippines - since her wedding to Prince Harry in 2018, she reached out after hearing about his surgery.
"I can confirm she has reached out to her father," a spokesperson for the Duchess of Sussex told Us Weekly.
Thomas's son Thomas Jr previously told the Daily Mail newspaper: "My dad is being very brave. His foot turned blue and then black. It happened very quickly. I took him to a local hospital, and they did some scans and an ultrasound and said the leg had to be amputated."
"There was no option. I was told the leg had to be removed, and it was a case of life or death."
Thomas, who is "stable" in the intensive care unit following the "life-threatening emergency, also needs to have a blood clot in his left thigh removed.
And his son said doctors remain "extremely concerned" for his dad's welfare.
"One of his doctors said the next two or three days are critical. His left leg has been removed below the knee. They were worried about infection setting in - sepsis or gangrene. The flesh was black and dying. There was no option given," Thomas Jr added.
"It was either, 'We have to operate now and remove the leg, or he may die.' It was a life-threatening situation."
Thomas moved to the Philippines earlier this year to create a new life away from the "constant pain" of having no communication with Meghan since she married Prince Harry.
Thomas - who has been in frail health in recent years - has also never met his grandchildren, Prince Archie, six, and four-year-old Princess Lilibet.
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