An autopsy report seen by local media confirmed she had been sexually assaulted, struck in the head and set alight, and at least one person has been arrested.
It follows the 2018 death of seven-year-old girl Zainab Ansari, whose raped body was also found among garbage near the city of Lahore, sparking waves of protests and accusations of negligence by Pakistani authorities.
According to non-profit child protection organisation Sahil, Pakistan sees nearly 10 cases of child abuse reported each day, most of them affecting girls.
Marwah’s death sparked an outpouring of rage and grief on social media, with many posts using the #JusticeForMarwah hashtag.
“When will this stop?” actress Armeena Khan asked in a Twitter post.
Pakistani international cricketer Shan Masood said it was “high time” to place "the utmost importance” on fighting the scourge of child abuse.
“We cannot lose our youth to such disgusting and inhuman acts. Keeping quiet is contributing to the issue. We must stand up to these cowards and take action,” he said on Twitter.
Footage uploaded to social media also appears to show a group of people protesting in city streets over the incident.
Earlier this year, Pakistan’s parliament passed a law against child abuse which requires police to register a case within two hours of a child’s parents reporting them missing.
The anger over Marwah's death comes days after thousands of Islamist protesters rallied across Pakistan over a French magazine's decision to republish cartoons of the Prophet Mohammed.
Charlie Hebdo, the target of a 2015 terror massacre, reprinted the controversial images last week to mark the beginning of the trial of the alleged accomplices in the attack.
If you or someone you know is impacted by sexual assault, family or domestic violence, call 1800RESPECT on 1800 737 732 or visit 1800RESPECT.org.au. In an emergency, call 000.