She contested from the NA-120 seat despite her failing health and secured 59,413 votes to defeat Yasmin Rashid of the Pakistan Tehreek-e-Insaf (PTI).
"COAS expresses his grief and heartfelt condolences to the bereaved family on the sad demise of Begum Kulsoom Nawaz".
FILE PHOTO: Ousted Prime Minister of Pakistan, Nawaz Sharif, speaks during a news conference at a hotel in London, Britain July 11, 2018. She had married Sharif in April 1971.
Ms Nawaz was born Kulsoom Rehana Butt in 1950 to a businessman and investor, Mohammad Hafeez Butt, and his wife Razia Begum. Her body will be brought back to Pakistan on the first available flight for burial.
Confirming the news Sharif's brother and the head Pakistan Muslim League-N, Shahbaz Sharif, tweeted from his party's official Twitetr handle in Urdu, "My sister-in-law and the wife of Nawaz Sharif sahib is no more amongst us".
Referring to her mother, Maryam Nawaz had said that she had dauntlessly challenged a usurper when "most men did not".
Nawaz Sharif was disqualified from holding public office by the Pakistan Supreme Court in the Panama Papers case.
For her undergraduate studies, Begum Kulsoom Nawaz attended the Forman Christian College and then pursued a Masters degree at the Punjab University.
But some observers pointed out that Kulsoom Nawaz was no political novice. According to some party leaders, she also occasionally wrote Mr Sharif's speeches.
She addressed rallies, gathered workers, and tried to lead Karvan Tahafuz Pakistan rally against Pervez Musharraf, after which the military ruler put her under house arrest.
Both her sons Hassan and Hussain reside in the United Kingdom and cared for her while Nawaz and Maryam attended near daily hearings of the corruption trial. But it soon transpired that she had been diagnosed with lymphoma. Due to her illness, Kulsoom was unable to return and formally take oath as a member of the National Assembly.