Members of Unison, GMB and Unite voted overwhelmingly in favour of the strike action, in response to the decision to set up a private Children's Trust.
Earlier this year it was decided that Sandwell's struggling children's services department, rated as 'inadequate' by Ofsted in June 2015, would be taken over by an independent trust.
The move was based on recommendations made by commissioner Eleanor Brazil, who was drafted in to oversee Sandwell's children's services.
However 97 per cent of Unison members have voted for a strike in a ballot against the changes. GMB members gave a 100 per cent vote for a strike ballot and Unite an 87 per cent vote.
The trade unions in Sandwell have now informed the Government's appointed commissioner of their intention to strike.
Tony Barnsley, joint branch secretary for Sandwell Unison said: "It is not a coincidence that the first four councils the Tories have enforced the privatisation of children's services are all Labour controlled.
"The enforcement of a Children's Trust upon Sandwell is being ideologically driven by the Tories set on privatising or cutting everything.
"There is simply no evidence or justification for privatising Children's Services in order to improve it.
"There are real practice fears it could adversely affect the service to Sandwell's children, particularly given the watering down of standards within current legislation."
The overhaul of children's services followed Ofsted identifying serious failures in its report last year.
The watchdog said that as a result of the 'inadequate' department children were being left at risk of harm.
A Sandwell Council spokesman refused to comment on the unions' actions.