The Prime Minister's eldest child, Nancy, is expected to be offered a place at The Grey Coat Hospital Academy.
The Church of England school receives around seven applications for every place and was rated outstanding by Ofsted.
If he wins the election this year it would mean David Cameron would be the first serving Tory prime minister to send his child to a state school.
Up to 151 girls are admitted to the school every year with around 80 having to come from a practicing Anglican background with a reference from a member of clergy.
Mr Cameron once said his Christian faith was a "bit like the reception for Magic FM in the Chilterns: It sort of comes and goes."
Staff at Grey Coat Hospital Academy have reportedly been told the Prime Minister's 10-year-old will be offered a place at the school within weeks.
Former Education Secretary Michael Gove also sends his child to classes there.
An official announcement is expected in March.