Spitting or throwing food out for birds and animals in Hounslow could now land you with a fine of up to £80.
The warning comes as the council announced 245 such fines have been handed out to litterbugs across the borough since the beginning of December - a record number for a three-month period.
Last week alone, 24 on-the-spot fines were issued by enforcement officers from the council and its street cleaning contractor Hounslow Highways.
Councillor Richard Foote, Hounslow Council's cabinet member for community protection, said: "The number of fines issued since the beginning of December is unprecedented in Hounslow.
"Never before has there been this kind of clamp down on grime crime in our borough. It shows we will not tolerate the selfish few who mess our streets."
The council last year applied for government permission to outlaw spitting in public, described by councillors as a "filthy act", after more than 5,000 people signed a petition backing the move.
In December, London Councils passed plans for a capital-wide by-law banning the act, subject to government approval.
Hounslow Council leader Steve Curran last September announced proposals to ban pigeon feeding, which he described as a "health hazard" and said attracted other vermin like rats.
Some other London boroughs had already been fining people for spitting and feeding animals in public, claiming both acts fell under the umbrella of littering.