Malik Ahmed Khan, the government spokesman in Punjab province said on Tuesday that the suspect was arrested near the city of Kasur where Zainab Ansari was killed earlier this month.
The provincial government spokesman noted that some of the suspect's accomplices are also in police custody.
Punjab Chief Minister Shahbaz Sharif during a press briefing in eastern city of Lahore thanked officials and members of intelligence agencies for tracking down the rapist
"The killer of Zainab has been arrested, his name is Imran, he is 24 years old and a resident of Kasur, he is a serial killer," Sharif said.
Sharif added that authorities conducted DNA testing of 1150 people and the DNA of Imran "100 percent' matched the evidence collected from the crime scene.
"Then in a polygraph test, the culprit confessed all of his wrong doings, we have the video recording," said Sharif.
Police said preliminary findings found DNA connecting the suspect to Zainab's murder. Investigators also found the same DNA on six of the 12 victims.
Zainab’s killing exposed a string of child abductions and slayings by a suspected serial predator. Pakistani officials had earlier said Zainab was one of twelve young girls that had been raped in the past twelve months in Kasur located near the Indian border. At least 11 of them were murdered.
Zainab was taken from near her home in Kasur on January 4 while her parents were on a pilgrimage. Her uncle reported her missing the next day.
Zainab's family said police did not respond after they reported their daughter's disappearance.
Zainab’s brutalized corpse was found in a trash pile about 100 meters from the family home five days after her disappearance.
An autopsy confirmed that Zainab was strangled and sodomized. There were torture marks on her face and Zainab's tongue was crushed between her teeth.
Television stations have repeatedly broadcast chilling CCTV footage purportedly showing the young girl walking hand-in-hand with an unidentified male in what may have been her last moments.
The brutal sparked fury across Pakistan with two people killed in riots in Kasur on January 10.
Kasur was previously at the center of a child sexual abuse scandal in which a gang of over two dozen men was accused of blackmailing scores of children into making sex videos between 2009 and 2014.
At least 280 children were sexually abused on camera by men who later blackmailed their families, threatening to leak the footage.
The abuse was uncovered in 2015 and multiple suspects were arrested.
According to Sahil, an aid group that works on child protection issues, there were 129 cases recorded in Kasur, including rape and murder from January to June 2017.