Oasis Academy Johanna, Waterloo's only primary school, has announced that it is expanding to two-form entry from September 2013.
This means that 60 reception places will be available from the start of the new school year in September.
The former Johanna Primary School gained academy status in September 2011. The expansion was agreed by the academy council in October.
The final open morning at Oasis Academy Johanna for new 2013 reception admissions is on Wednesday 9 January at 9.30am.
In January Lambeth councillors will consider a planning application for the conversion of the former Government offices at Hercules House into a new home for the Oasis Academy South Bank secondary free school which is also due to open in September next year.
The plans for Hercules House include space for extra primary classes for Oasis Academy Johanna.
This week Lambeth's cabinet discussed the future demand for school places in the borough.
The report presented to cabinet members warned that the proposed Oasis Academy South Bank is in "the wrong part of the borough" with project demand for secondary school places being higher in the south of Lambeth than in Kennington and Waterloo.
However Cllr Sally Prentice, Labour cabinet member for culture and leisure, told the meeting that she believed that the new free school would provide much-needed extra choice for local families.
At present the only secondary school in the far north of Lambeth is the boys-only London Nautical School.
"I actually welcome the Oasis Academy in Waterloo because I think the choice for girls in the north of the borough is actually quite limited," said Cllr Prentice.
"If you're a parent in the south of the borough and you are looking for a non-denominational school you actually have quite a good choice: you have Elmgreen, Dunraven, the Charter School and other schools in Southwark; that is not necessarily the same in the north of the borough."
The Lambeth cabinet consideration of future school places made no mention of the expansion of Oasis Academy Johanna, nor of the recently announced King's College London mathematics post-16 free school proposed for Waterloo.