Nine terror-related offences will be added to the scheme that handles complaints that sentences are too soft from Monday.
Criminals convicted of tipping off terrorists about investigations and suspects who flout anti-terror court orders are among those who could see their punishments queried under the expansion.
Justice Minister Rory Stewart said: "People who assist terrorists or fail to alert authorities to terrorist activity must be severely punished.
"These changes ensure victims can challenge sentences that don't look right, and make sure that they have every opportunity to see justice delivered."
Under the Unduly Lenient Sentence (ULS) scheme, anyone can ask the Attorney General to examine sentences they believe to be too light.
Cases are reviewed and can be sent to the Court of Appeal, which will then determine whether the penalty should stay the same, or be increased.
Last year, a record 141 criminals had their sentences increased under the initiative.
The Ministry of Justice noted that this is a small proportion of the 80,000 cases heard by Crown Courts each year.
Plans to include the nine offences were first announced last month.