Several senior ministers, including Health Minister Harsh Vardhan, reached AIIMS after she was admitted to the hospital.
Swaraj had put out a tweet in the evening congratulating Prime Minister Narendra Modi after the Centre's move to revoke special status for Jammu and Kashmir and bifurcate the border state into two Union Territories secured Parliament's approval.
"Narendra Modi ji - Thank you Prime Minister. Thank you very much. I was waiting to see this day in my lifetime," she had said.
Swaraj had a kidney transplant in 2016 and had opted out of contesting Lok Sabha polls earlier this year for health reasons. She is survived by her husband Swaraj Kaushal and daughter Bansuri.
Prime Minister Narendra Modi on Tuesday condoled the demise of former Union minister Sushma Swaraj, saying a glorious chapter in Indian politics had come to an end.
"A glorious chapter in Indian politics comes to an end. India grieves the demise of a remarkable leader who devoted her life to public service and bettering lives of the poor. Sushma Swaraj Ji was one of her kind, who was a source of inspiration for crores of people," he tweeted.