Plans for the project include a 2,600 m2 single-storey main building with 14 classrooms, a nursery and a hall.
The new building will have capacity for 450 pupils, including 60 of pre-school age.
External amenities include car parking, two multi-use games areas and a grass sports pitch.
Hirwaun Primary School’s existing teaching blocks will be demolished in phases as construction of the new building proceeds.
Overall project budget is £10.2m.
The main contractor won the project through the Southeast & mid-Wales collaborative construction framework (SEWSCAP).
Work is expected to complete on the project by spring 2021.
This is the fourth school Morgan Sindall Construction will build for Rhondda Cynon Taf under the Welsh government’s 21st century schools programme.
Rob Williams, area director for Morgan Sindall Construction, said: “We are excited to begin work on Hirwaun Primary School and to continue our delivery of modern learning environments in South Wales through SEWSCAP. We’ve established a great collaborative relationship with the council and the track record of well-received schools speaks to the effectiveness of long-term partnership.”
Councillor Joy Rosser, Rhondda Cynon Taf Council’s cabinet member for education and inclusion services, added: “The council has a good working relationship with Morgan Sindall Construction, which was the contractor for the fantastic £7.2m Cwmaman Primary School, delivered on schedule in September 2018, with excellent engagement with the community throughout its construction.”