The achievement was marked at a ceremony at its Ganewatte site attended by British high commissioner to Sri Lanka John Rankin.
He said: "It is here in rural Sri Lanka in particular that the economic benefits of the Cocogreen success story are most visible. The potential social and economic benefits are enormous, helping Sri Lankans tackle poverty in areas where employment is most scarce."
Cocogreen has four factory processing sites in Sri Lanka, a laboratory and research and development site. It employs 300 full-time workers with a further 300 working up to 10 months of the year.
Manchester-based sales and marketing director Thomas Ogden said: "Earlier this year we gained the quality ISO9001:2008 accreditation across all our Sri Lankan production facilities and became the first quality coir substrate manufacturer to join LEAF (Linking Environment & Farming).
"We have now gained SA8000 accreditation, which measures social compliance. This certification standard is based on conventions of the UN and the International Labour Organisation, and is independently audited."
Cocogreen is unusual among substrate suppliers in being highly vertically integrated, controlling the supply chain from the raw material, harvested from its own coconut plantations, through to the final value-added product and technical support.