Saeed, who heads terror group Jamaat-ud-Dawa (JuD) and has a $10 million US bounty on his head, has been under house arrest since January following a crackdown on the outfit by Pakistan.
"Hafiz Saeed's detention has been extended for a period of one-month," a senior government official told AFP on condition of anonymity.
He said the detention was extended by a three-member review board of Lahore High Court headed by Judge Yawar Ali.
JuD, listed as a terror outfit by the United Nations, is considered by the US and India to be a front for Lashkar-e-Taiba (LeT), the terrorist group blamed for the attack on Mumbai which killed more than 160 people.
The government has been sceptical that any action will be taken against Saeed by Pakistan despite his arrest.
Despite the bounty against him, Saeed led a high-profile public life in Pakistan until his arrest, regularly delivering anti-India speeches.