Fifty terrorist prisoners must now serve at least two-thirds of their prison term before they are considered eligible for release.
Mohammed Zahir Khan was jailed in 2018 for four years for encouraging terrorism, dissemination of a terror publication and stirring up religious hatred
The government rushed the Terrorist Offenders (Restriction of Early Release) Bill through parliament, after two former terrorist prisoners went on to launch attacks in London within two months of each other.
The change will affect around 50 prisoners, due for automatic release halfway through their sentences, making sure they now serve at least two-thirds of their prison term before they are considered eligible for release.
Before being freed, they will now also need to pass a review by a panel of specialist judges and psychiatrists at the Parole Board.
Sunderland shopkeeper Mohammed Zahir Khan, who was jailed for four-and-a-half years in May 2018, was due for release on 28 February.
He was arrested after posting extremist material online calling for a year of fear and pledging support for the terror group ISIS.
The change in legislation will allow authorities to keep him in prison for another year, before he is considered for parole.