The decision followed the greenlight on Tuesday by Washington, all but sealing the buy-out despite growing resistance.
"ChemChina has offered significant remedies, which fully address our competition concerns. This has allowed us to approve the transaction," EU Competition Commissioner Magrethe Vestager said in a statement.
The decision followed the greenlight on Tuesday by Washington, all but sealing the buy-out despite growing resistance in the US and Europe to blockbuster takeovers by Chinese companies.
The deal combines Syngenta, a global leader in seeds and crop protection, with ChemChina which controls Adama, the largest supplier of generic crop protection products in Europe.
The merger is part of a broader wave of consolidation in the agro-chemicals sector that has worried environmental activists and farmers.
The EU last week approved the $130-billion merger of US agro-chemicals giants Dow Chemical and DuPont and it will also decide on German giant Bayer's $66-billion offer for US firm Monsanto.
The Commission said that ChemChina had satisfied its competition concerns with the sale of "a significant part of Adama's existing pesticide business."
This, along with other divestments, "will ensure that effective competition is preserved in pesticide and plant growth regulator markets after the takeover," it said.
The US Federal Trade Commission had given its go-ahead to the buyout by China National Chemical Corp on the condition that it stopped producing three pesticides to avoid monopoly conflicts.
Given the global scope of the deal, the Commission said it had cooperated closely with other competition authorities, notably in the United States, Brazil and Canada.