Wandsworth Council has decided to axe all of its school crossing patrols, in a bid to save £200,000 a year.
The Tory-controlled council says that virtually all young children are now taken to school by their parents and that older children "cross roads that do not have patrollers perfectly safely every day".
A spokesman added that they were talking to schools about how they could best provide the service if they wished to keep it.
They said: "At a time when statutory town hall services are facing severe budget constraints, it is only fair that schools which benefit from this service are asked if they are prepared to pay for it.
"The council recognises its wider road safety responsibilities and has an excellent record in delivering safety improvements to the borough's road network."
Paul Maloney, national officer of the GMB, branded the move "a disgrace".
He said: "David Cameron said frontline services would not be cut but there are few more frontline than lollipop staff stopping children being knocked down on the roads.
"Tory Wandsworth is always first with cuts like this as the Tories there have not changed from being the nasty party."