The house builder specialises in constructing low carbon homes using timber frame panels manufactured at its factory in Bicester.
M&G acquired a majority stake in the firm in 2022 for £15m.
Latest accounts for Greencore for the year to May 31 2023 show a pre-tax loss of £4m from a turnover of £579,800.
The company said the new funding will initially go towards land acquisitions as it aims to build 10,000 homes in the next decade.
Greencore currently has around 40 employees and is led by industry veteran Jon Di-Stefano who joined the company as Chief Executive in October 2022.
Di-Stefano said: “Our vision is to lead the housebuilding industry in the delivery of climate positive homes and M&G’s further investment reflects their confidence in our potential to take on this role and operate at scale.
“This investment will enable us to secure the land needed to deliver on our targets whilst supporting local communities, jobs and the environment. We look forward to continuing our strong relationship with M&G while we seek out new partnerships to help bolster our pipeline and support our target of building 10,000 climate-positive homes.”