Speaking to delegates at the Conservative Spring conference in Gateshead, Mr Cameron said he would make the service more universal and give all new mothers a guaranteed level of support if his party win the next general election.
The service has gone into freefall under Labour, according to Mr Cameron who said too much had been invested in Surestart outreach workers.
Mr Cameron said: 'We're going to radically increase the number of health visitors so that every family can count on the proper, professional support they need.
'With money set aside for proper training and extra help for families in the most deprived areas.
'Health visitors are the kind of support that parents want.'