Internet users who encourage self-harm could be jailed for up to five years under Government plans.
The addition to the Online Safety Bill will build on existing laws which make it illegal to promote or assist suicide, the Ministry of Justice (MoJ) said.
The measures seek to deter “cowardly trolls” who post such content online with the prospect of prosecution, according to Justice Secretary Alex Chalk.
Posts would not need to target a specific individual or group to pass as an offence.
General encouragement of self-harm, starving and not taking prescribed medication will be covered by the law, the MoJ said.
Ministers previously announced the promotion of self-harm would be criminalised but on Thursday confirmed the maximum penalty for the offence upon conviction would be imprisonment for five years.
It comes after former culture secretary Nicky Morgan accused Government of “condoning” dangerous online content by rejecting calls to make such material filtered out by default.
The Tory peer urged ministers to make an addition to the Bill to require users to “flip a switch” if they want to opt in, rather than opt out, to the most harmful material.
Justice Secretary Alex Chalk said: “There is no place in our society for those who set out to deliberately encourage the serious self-harm of others.
“Our new law will send a clear message to these cowardly trolls that their behaviour is not acceptable.
“Building on the existing measures in the Online Safety Bill our changes will make it easier to convict these vile individuals and make the internet a better and safer place for everyone.”
The measures adopt a 2021 Law Commission recommendation that individuals responsible for encouraging or assisting serious self-harm should be better held to account by criminal law.
They follow the case of Molly Russell, a teenage girl who took her life after being exposed to graphic self-harm and suicide content online.
While the Bill would establish a higher level of protection for children, that protection would be removed once they turn 18, and all adults would be exposed to harmful content, unless they choose to opt out.