The two-year-old had been suffering with leukaemia and her family's campaign to raise awareness of her battle touched the hearts of millions.
The brave youngster was diagnosed with both acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML) last October.
A Swab4Margot campaign, backed by celebrities such as Stephen Fry and John Bishop, led to more than 50,000 people requesting swab kits from charity Delete Blood Cancer UK.
Her parents Vicki and Yaser, originally from Essington, kept people aware of her progress on their Facebook page.
A statement today released by her family said: "At 10.24am this morning, our dear little daughter, Margot passed away at home.
"She died peacefully and was surrounded by those who love her.
"Thank you for all your love and support. Vicki, Yaser, Oscar and Rufus."