Contractor Morrison Construction will be onsite from Monday 3 April to start the process of building the replacement school.
The site for the new facility is next to the existing school in Langton Road, East Calder, with the recently-built Early Years extension retained.
The new school will be complete by August 2024, when pupils will move into the replacement building and work will then commence to demolish the current school and complete the remaining external works.
Executive councillor for education Andrew McGuire said: "I was delighted to visit East Calder Primary School and see the plans for a fantastic new replacement school first hand.
"West Lothian already has one of the best school estates in Scotland and ongoing investments like this will deliver huge benefits for the community when complete."
Due to the close proximity with the current school, the Easter holidays period when pupils are not in school was chosen to limit disruption and allow the construction area to be safely set up.
The scale of this project means local residents can expect increased construction traffic around East Calder town centre.
Parents/carers in the local community are also advised to make sure their children and young people are aware of the potential dangers of construction sites and to keep clear of the site.
East Calder Headteacher Fiona Stewart said: "The whole East Calder Primary school community is very excited about our new purpose-built school and the many benefits it will bring to enhance learning experiences for our children.
"We are looking forward to the potential opportunities for learning that the construction process will afford us throughout the build process."
The project is being delivered on behalf of the council by Hub South East with Morrison Construction as the Tier-1 contractor. This is the same partnership that recently delivered the new multi- school Winchburgh Schools development, West Calder High School and Calderwood Primary in East Calder.
Eileen Mackin, Hub South East's Project Director said: "The pupils and staff of East Calder Primary are clearly excited about their new learning space, so it's great to be able to start making the plans a reality.
"We look forward to ensuring that the construction progresses safely and to programme and that a range of social value initiatives are delivered locally, ensuring that the wider community benefits from opportunities on site, from work experience and site visits to apprenticeships and new jobs."
David Ewing, Managing Director of Morrison Construction Building Central, commented: "We have a tremendous collaborative relationship built over many years with West Lothian Council and Hub South East.
"We are looking forward to East Calder becoming yet another fantastic school to add to the portfolio of award-winning projects we have built together, and providing the high-quality facilities safely that students and staff deserve."
The current East Calder Primary School building is not suitable for the future delivery of high-quality education due to a number of issues including suitability, accessibility and sustainability. Due to rising construction costs, a fixed price of £18.3 million has been agreed to remove additional financial risks.
It is jointly funded by Scottish and Local Government as part of the Learning Estate Investment Programme.
