British authorities thwarted more than 150 attempted journeys to the conflict in Iraq and Syria last year.
This includes action by the family courts, which have increasingly been taking measures to prevent travel, an official report revealed.
It said courts protected approximately 50 children from being taken to the conflict area in 2015.
The figures were revealed in the Government's annual report on the counter-terrorism strategy, known as Contest.
It said reducing the risk from people travelling to and returning from the conflict in Syria and Iraq "was a major focus of our work" last year.
Around 850 individuals of national security concern have made the journey since the conflict started. Just under half have returned to the UK and approximately 15% are dead.
The report said that over the course of 2015, fewer people travelled from the UK to the area than in previous years.
It added: "The police and other partners have used a wide range of methods to prevent travel to the conflict.
"More than 150 attempted journeys to the conflict area were disrupted in 2015.
"This includes action by the family courts, which have increasingly been taking measures to prevent travel. The courts protected approximately 50 children (from around 20 families) from being taken to the conflict area in 2015."
The report outlined the use of powers to disrupt suspected terrorist activity where prosecution is not possible.
The Royal Prerogative can be exercised against British passport holders to cancel, or refuse to issue, a passport on public interest grounds.
It can be used to disrupt individuals who seek to travel to engage in terrorism, and the power was used 23 times last year.
Another measure allowing police to seize and temporarily retain travel documents at ports to halt immediate travel was exercised 24 times between February and December.
Publishing the report, Home Secretary Amber Rudd said: "Keeping our people and interests safe - both here and overseas - is the primary duty of Government.
"The horrific attack in Nice last week was the latest terrible reminder that the threat from terrorism is more acute and more complex than ever before."