Mohammad Imran was hanged in a Lahore prison in the presence of Amin Ansari, the father of one of his victims.
The rape and murder of Ansari's 7-year-old daughter Zainab in January triggered a worldwide outcry.
Hanging took place in the early morning of October 17 and the corpse was handed over to the man's family, said prison officer Muzaffar Awan.
Imran was arrested two weeks after Zainab was found in a garbage dump in the city of Kasur near Lahore in January.
The police said the girl had been raped and strangled. Imran confessed to having assaulted and killed seven other children during the interrogation.
Ansari, who was allowed by a court to watch the execution, said he was satisfied after seeing his daughter's murderer "dreadfully" die.
"I feel that justice has served," Ansari told Pakistan's Geo-TV.
Nearly 3,500 children are physically assaulted each year in Pakistan, and most robbers are outlawing law because of legal and social issues, said Gohar Mumtaz of the Sahil charity.