Work to prepare a site in Nelson for 200 new homes and more than 6,000 sqm of employment space have begun.
The development on Welsh Government-owned land at Ty Du, near the large Co-op store, was granted outline planning permission by Caerphilly County Borough Council in October 2016.
Out of the 200 new homes, around 50 will be affordable.
Construction work to prepare the site, which will be undertaken by civil engineering contractor, Walters UK, is being funded by £4 million of investment from Welsh Government including £2.5m of EU funds.
Work is scheduled to be completed in mid 2019.
Speaking following a meeting of the Valleys Taskforce, Economy Secretary Ken Skates AM said: “Good quality jobs are one of the priorities of our high-level action plan for the South Wales Valleys, Our Valleys, Our Future.
“However one of the challenges in providing good quality jobs is ensuring the right business space is available at the right location.
“We know that there is currently a lack of high-quality standalone development sites in the mid Valleys area that are ready for development and well connected to local infrastructure.”