Wahab, who was a member of parliament and the deputy political secretary to President Asif Ali Zardari, died at a private hospital in Karachi.
She went into a coma after remaining in a critical condition for about three weeks due to complications after a gall bladder surgery.
She is survived by two sons and a daughter.
A student of international relations from the University of Karachi, Wahab entered politics as a student leader and campaigned for human rights.
She held several important positions in the PPP and was a close aide of slain former premier Benazir Bhutto.
President Asif Ali Zardari and Prime Minister Yousuf Raza Gilani condoled Wahab's death.
In a message, Zardari paid tribute to her services to the PPP and said she was a loyalist who braved difficult situations.
Gilani expressed sorrow at her death and said she was a committed worker who stood for the promotion of democracy and human rights.
"Her death is a great loss to the party and she has left a void that can't be fulfilled," PPP leader, Sharmila Farooqi said.
Moving scenes were witnessed outside the ICU of the hospital where leaders of the PPP and Mutthaida Qaumi Movement had gathered.
"She has passed away due to negligence of the doctors and the government will hold an inquiry into this," MQM Member National Assembly, Babar Ghouri said.
Fauzia Wahab had been in the hospital for the last 23 days.
Islamabad/Karachi: Senior Pakistan People's Party leader Fauzia Wahab, who was a leading campaigner for democracy and human rights, died on Sunday due to complications following surgery at the age of 56.
First Published: Monday, June 18, 2012, 00:30