"My mother died fighting for a peaceful, prosperous and progressive Pakistan. I will never give up on my mother's Pakistan. I will never give up on the woman who sacrificed herself so Pakistan could be free," Bilawal wrote in an article marking the fourth anniversary of Bhutto's assassination.
"Her dreams are now my dreams ?" that is my promise to you; that is my promise to her," wrote the 23-year-old who has begun playing a larger role in the affairs of the PPP since his father, President Asif Ali Zardari, was embroiled in the Memogate scandal last month.
Referring to his mother's killing by a suicide attacker in Rawalpindi four years ago, Bilawal wrote in The Express Tribune: "Had we chosen the path of revolution over evolution on that fateful December 27, both the army and the (PPP) would have been weakened. That would have left the only other armed group, the terrorists, with the opportunity to exploit the situation and seize control of our country.
"We must remain committed to the evolution of a democratic Pakistan and reject the calls for confrontation between institutions," he wrote against the backdrop of continuing tensions between the civilian government and the powerful military over the alleged memo that had sought US help to stave off a feared coup in Pakistan in May.
The PPP wanted both a "strong military" and an "independent judiciary", Bilawal said.
"We have always supported an independent judiciary and would never let the abuses of individual judges in the past sabotage our mission of establishing a free, impartial and independent judiciary," Bilawal wrote.
"This is why we knew in 2007 that we had to distinguish between (former military ruler Pervez) Musharraf and the army as an institution. A strong military is needed in order to protect our territorial borders and defeat the internal cancer of Islamist extremism," he added.
Bilawal said the politicisation of the military under dictatorship "engages it in arenas where it has no place and, as a result, weakens its ability to perform its primary function".
The PPP would continue to back "reconciliation and not violent revolution". The transition to democracy has borne fruit and the elected government "gave ownership to the fight against extremists and made it Pakistan's war", he said.
"It is only under a democratic government that Pakistan finally stood up to demand respect from the US and to do what the dictator with all his military might could not ?" evacuate the Shamsi airbase," Bilawal wrote in a reference to actions taken by Pakistan after a cross-border NATO air strike killed 24 Pakistani soldiers last month.
Pakistan has "onerous challenges" before it and the "push for economic and energy reform must go forward, as must our promise to build a Pakistan where education is the path to empowerment", he added.
Paying tribute to his mother, Bilawal said he was "most focused on what she might have accomplished had she lived".
He lauded her role in promoting education, women’s rights and healthcare, and promotion of technology and the media.
"It was an amazing record of accomplishment, made even more remarkable by the constraint of aborted tenures, by constant pressure from a hostile establishment and presidents with the power to sack elected governments," he wrote.