Oxford-based Eden, which specialises in creating low-risk agricultural chemicals, said that 3AEY - its first agrochemical product – has been authorised for use in the Baltic state.
The chemical targets botrytis - a fungus that affects many plant species, most notably wine grapes.
Bulgaria is in the top 20 wine producing countries globally, and wine grapes make up the vast majority of Bulgarian production.
It’s now the third of seven countries in the southern EU zone to grant approval for 3AEY, which apparently carries no negative quality effects on table grapes or when used to produce wine.
Malta and Greece have already approved the product and Eden's partners Redestos, Sipcam and Sumi Agro France are now preparing for product launches following authorisation.
"Authorisation of 3AEY in Bulgaria is an important additional milestone for Eden and its regional commercialisation partner, Redestos,” says Eden's chief exec Sean Smith.
“Though outside of our control, we continue to anticipate authorisation in the remaining member states in due course, and in time for this year's growing season.
“Our partners are already preparing for official commercial product launches in 2016 across the region."
Shares in Eden were 5 per cent higher, reaching 14.5p an hour after the London market opened.