The weapon was found on Bellhouse Road, in Shiregreen, which has become a hotbed of crime and antisocial behaviour in recent months.
Just last Wednesday, PCSO Jimmy Staniforth was left with a bloodied face after being pelted by yobs on the estate with stones, one of which hit him just below eye.
That attack took place on Hatfield House Lane, which is just of Bellhouse Road.
The photo of what appears to be a kitchen knife, with a blade just under four inches long, was posted on Facebook this evening by the Sheffield North East neighbourhood policing team.
It was accompanied by the message: "Knife found by PCSOs whilst out on patrols on Bellhouse Road, Shiregreen."
Embattled residents on the estate have complained for months now about youths hurling stones and bottles at passing cars and pedestrians, damaging property and abusing and intimidating locals.
Police have recently stepped up patrols on the estate, used dispersal powers to move on potential troublemakers and introduced CCTV cameras.
They have also written to the parents and carers of those believed to be responsible warning them of the potential consequences, which include losing housing tenancies.