|The knife crime consultation will take place in the autumn|
It is already an offence to sell knives to under-18s but the planned measures would mean they cannot be delivered to private property.
Online buyers would have to pick up any knife bought from a shop, where they would also be required to show proof of age.
Announcing her intention to tighten the law, Home Secretary Amber Rudd said: "We are announcing new measures to combat knife crime and the devastating impact it has on families, individuals and communities.
"We are going to be consulting on new legislation so that people can't buy knives online without having their identity checked.
"At the moment you have to do it by the click of a button.
"What we are proposing is that if you want to buy a knife online it has to be collected from a place where you have to show your ID.
"We have evidence that young people have been able to buy knives without verifying their ID and I want to stop that."
Calls for action on internet sales intensified last year after a court heard a knife used in the fatal stabbing of Bailey Gwynne, an Aberdeen schoolboy, was purchased online.
The knife crime consultation will also aim to close a loophole that means police can be powerless to act if they discover knives in someone's home.
A ban on the possession of outlawed weapons such as zombie knives and knuckledusters on private property would mean officers can seize them and make arrests.
The consultation will also ask if the offence of possessing a knife in a public place and school should be extended to universities.
Recent national crime figures showed the majority of police forces - 33 out of 44 - registered a rise in offences involving knives and sharp instruments last year.
Officers say youths are keeping blades on them for reasons including "status" and self-protection, as well as crime.