Construction of five new primary schools has been announced for Perth's expanding outer suburbs at a cost of more than $80 million.

Three new primary schools will be built south of the river in Baldivis, Harrisdale and Southern River.

One school will be constructed in the north-east suburb of Brabham, while a fifth will be added in Yanchep on the city's northern coastline.

WA Education Minister Sue Ellery said the new schools would help deal with urban sprawl and the rising population in the outer suburbs.

"This is going to help us keep up with it," Ms Ellery said.

"That's why we've made a deliberate decision to announce five different additional schools.

"It wasn't in the plan we inherited, so we've added the extra schools to keep up with the growth."

Hundreds of construction jobs

Ms Ellery said the schools would be paid for with "new" money from the state budget, but she would not be drawn on any further detail about where the money had come from.

Construction on four of the schools would begin in 2019, with one to begin construction the following year. All five schools were due to open in 2021.

At least 400 construction jobs are expected to be created.

WA Premier Mark McGowan, with Tenara (4) and Ella Papali (4), says the new schools will cost $80 million. ( ABC News: Eliza Laschon )

The schools in Baldivis and Yanchep would accommodate 430 students from kindergarten to Year 6, while the remaining schools would accommodate 540 students each.

Eight other primary schools across Perth and its outer suburbs were set to open over the next two years.

That included the Aspiri Primary School in Piara Waters, which would open its doors to years 1 to 6 students next year.

It has already been opened to pre-primary and kindergarten students.

WA State School Teachers Union president Pat Byrne welcomed the announcement.

"We had noted that in the May budget this year there was in fact no provisions for any new schools to be built at all, which is highly unusual, so we certainly welcome the recognition that we do continue to have new schools," Ms Bryne said.

"We've got a steady increase in enrolments in public schools and that's been the case for some years now, and obviously the Government is moving to build schools in those suburbs which have the most need.

"The enrolment increase in public schools is forecast to continue for the foreseeable future so there's no question that these schools are necessary and that more in fact will also be necessary."