Domestic abusers who control their victims through social media accounts or spy on them online could now face up to five years in prison.
New powers will target perpetrators who subject spouses, partners and other family members to serious psychological and emotional torment but stop short of violence.
Legislation that comes into force today paves the way for charges to be brought in domestic abuse cases where there is evidence of repeated "controlling or coercive behaviour" for the first time.
The Crown Prosecution Service said the type of abuse covered by the new offence could include a pattern of threats, humiliation and intimidation or stopping someone from socialising, controlling their social media accounts, surveillance through apps and dictating what they wear.
Director of Public Prosecutions Alison Saunders said: "Controlling or coercive behaviour can limit victims' basic human rights, such as their freedom of movement and their independence.
"This behaviour can be incredibly harmful in an abusive relationship where one person holds more power than the other, even if on the face of it this behaviour might seem playful, innocuous or loving.
"Victims can be frightened of the repercussions of not abiding by someone else's rules. Often they fear that violence will be used against them, or suffer from extreme psychological and emotional abuse.
"Being subjected to repeated humiliation, intimidation or subordination can be as harmful as physical abuse, with many victims stating that trauma from psychological abuse had a more lasting impact than physical abuse.
"These new powers mean this behaviour, which is particularly relevant to cases of domestic abuse, can now be prosecuted in its own right."
The Government announced the creation of the new offence of controlling or coercive behaviour last year after 85% of respondents to a consultation said the law does not currently give sufficient protection to victims.
Coercive behaviour is defined as a continuing act or pattern of acts which are used to harm, punish or frighten a victim.
Controlling behaviour covers a range of conduct designed to make a person subordinate or dependent.
Examples could include:
:: Stopping a victim from socialising.
:: Limiting access to family, friends and finances.
:: Monitoring a person via online communication tools, for example using tracking apps on mobile phones.
:: Threats to reveal or publish private information.
Cases will be heard in either magistrates' or crown courts and the maximum sentence is five years imprisonment, with evidence potentially including emails and bank records.
Home Office guidance says that in order for the offence to apply the pattern of behaviour alleged must have a "serious effect" on the victim.
This means they must have either feared violence will be used against them on at least two occasions or they have been caused serious alarm or distress which has a "substantial adverse effect" on their usual day-to-day activities.
Police and prosecutors are being trained to recognise patterns of abuse behaviour which meet the criminal threshold.
Earlier this month police watchdogs revealed there has been a "staggering" increase in reports of domestic abuse, with recorded crimes jumping by almost a third in less than two years.
Louisa Rolfe, national police lead on domestic abuse, said the new offence "will provide more opportunities to evidence other forms of domestic abuse, beyond physical violence".
David Tucker, of the College of Policing, said: "The new offence of coercive control presents challenges - it demands much fuller understanding of events that led up to a call for assistance and this can make evidence gathering more complex.
"However, more importantly, it delivers greater opportunities to safeguard victims and achieve successful prosecutions.This is a real opportunity for the police service and CPS to work together to make victims and potential victims of serious assaults safer."
Polly Neate, chief executive of Women's Aid, said it was a "landmark moment" in the approach to domestic abuse.