Every internet user will be forced to opt in if they want to access internet pornography in a new crackdown spearheaded by David Cameron.
Possessing violent pornography showing simulated rape scenes will also be made a crime in England and Wales under the Prime Minister's plans.
Mr Cameron has also set out steps to subject videos streamed online in the UK to the same restrictions as those sold in shops.
And he warned internet giants they could face tough new laws if they fail to blacklist key search terms for horrific images by this October.
In an emotive speech, the Prime Minister warned that access to online porn is "corroding childhood" and demanded tough action by search engines such as Google.
Under his plans, internet service providers (ISPs) will introduce a "default on" filters that will oblige homeowners to "opt in" to receive sexually graphic material.
The filter will be automatically enabled for new customers setting up broadband accounts or switching providers unless a request is made to disable it.
Mr Cameron said: "In the darkest corners of the internet, there are things going on that are a direct danger to our children, and that must be stamped out.
"I feel profoundly as a politician, and as a father, that the time for action has come. This is, quite simply, about how we protect our children and their innocence."
The internet industry has already agreed to use a database to proactively scan, block and remove any unacceptable images wherever they occur.
But Mr Cameron says they have a "moral duty" to go further and need to work out further measures to block access to content by focusing on searches for particular phrases.
The Government is "already looking at the legislative options we have to force action", the Prime Minister said.
He added that firms could not just stand by and blame "technical obstacles" and urged them to use their "great brains to overcome them".
Mr Cameron pointed out: "You are the people who have worked out how to map almost every inch of the earth from space, who have algorithms that make sense of vast quantities of information."
He also called for warning pages which pop up if people try to access illegal content to spell out more explicitly the consequences of their actions.
In a statement, a Google spokesman said: "We have a zero tolerance attitude to child sexual abuse imagery. Whenever we discover it, we respond quickly to remove and report it.
"We recently donated $5m (£3.28m) to help combat this problem and are committed to continuing the dialogue with the Government on these issues."
Women's groups and academics who have campaigned to close the "rape porn" loophole welcomed the plans.
Holly Dustin, director of the End Violence Against Women Coalition, said: "We are delighted that David Cameron has responded to the call by experts and women's groups to ban pornographic images of rape that promote and eroticise violence against women.
"The coalition Government has pledged to prevent abuse of women and girls, so tackling a culture that glorifies abuse is critical for achieving this.
"The next step is working with experts to ensure careful drafting of the law and proper resourcing to ensure the law is enforced fully."
Experts from Ceop will be given enhanced powers to examine secretive file-sharing networks, and a secure database of banned child porn images gathered by police across the country will be used to trace illegal content and the paedophiles viewing it.
Mr Cameron, who has faced criticism from Labour over cuts to Ceop's funding, insisted that the centre's experts and police will be given the powers needed to keep pace with technological changes on the web.
He also set out proposals to link the storage banks of illegal imagery held by police forces across the country to produce a single, secure database enabling officers from different areas to work together to "close the net on paedophiles".
However, former Ceop chief Jim Gamble - who resigned in protest over its merger with the National Crime Agency - warned sex abusers would simply "laugh" at the plans and called for greater action.
"This Government has stood still for two years with regard to Ceop," he claimed. "Ceop's budget has in real terms decreased.
"There are 50,000 predators we are told by Ceop downloading images from peer-to-peer, yet from Ceop intelligence only 192 were arrested last year. That's simply not good enough.
"We have got to get the balance right. The balance is attack the root cause, invest with new money into child protection teams, victim support and policing on the ground.
"Let's create a real deterrent, not a pop-up that paedophiles will laugh at."
Sky News
