Crossbows, air rifles, batons and flick knives have been ordered online and seized by the postal service in the past eight months, police say.
Since April the Southern Community Action Team at Cambridgeshire Police have been alerted to 24 incidents of weapons being bought.
The items have been seized by customs or the postal service due to being illegal to buy under the Importation of Offensive Weapons Act 1959.
Weapons advertised online range from nun chucks to tasers and batons.
A spokesperson for Cambridgeshire Police said: "While we realise how accessible these weapons may seem, it is an indictable offence to buy them and the team act on any information they received in relation to these kinds of offences.
"Know someone who carries a weapon? Please help us tackle serious street-based violence and report it to us by calling 101 or visiting www.cambs.police.uk/report.
"Alternatively, contact Crimestoppers, anonymously, on 0800 555111 or via www.crimestoppers-uk.org."
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