Based in Basel, Switzerland, Syngenta was formed in 13 November 2000 by the merger of Novartis Agribusiness and Zeneca Agrochemicals.

Novartis was formed of the 1996 merger of the three Swiss companies: Geigy, which has roots back to 1758; Sandoz Laboratories which was founded in 1876; and Ciba, founded in 1884.
Ciba and Geigy merged in 1971.

Zeneca Agrochemicals was part of AstraZeneca, and formerly of Imperial Chemical Industries.
ICI was formed in the UK in 1926.
Two years later, work began at the Agricultural Research Station at Jealotts Hill near Bracknell.

In 2004, Syngenta Seeds purchased Garst, the North American corn and soybean business of Advanta, as well as Golden Harvest Seeds.
On 5 December 2004,  the European Union ended a six-year moratorium when it approved imports of two varieties of genetically modified corn sold by Monsanto and its Swiss rival, Syngenta.

In 2005, Syngenta opposed a Swiss ban on genetically engineered organisms.
On 28 November 2005, Switzerland enacted a five-year ban on the farming of genetically modified crops, underscoring the problems facing the European Commission and biotech companies like Syngenta, Bayer and Monsanto as they try to overcome consumer doubts about safety.

As of 2014 Syngenta's main competitors were Monsanto Company, BASF, Dow AgroSciences, Bayer CropScience and DuPont Pioneer.

In 2014, Monsanto sought to acquire Syngenta for a reported $40 billion, but Syngenta rejected the offer.
Since April 2015 Monsanto and Syngenta had been working with their investment banks Morgan Stanley and Goldman Sachs respectively on a deal.
The U.S. Treasury tried to stop the deal for tax inversion.
Syngenta's Board of Directors rejected an even better offer by Monsanto during August 2015, and Monsanto withdrew from the negotiations on 26 August.

According to the Swiss business weekly, Finanz und Wirtschaft, many Syngenta shareholders were enraged, both by the company's refusal to enter into takeover negotiations with Monsanto, and with the subsequent offer withdrawal.
This resulted in a group of investors responding by creating the Alliance of Critical Syngenta Shareholders, which urged the Board to "evaluate all options for value creation without prejudice".

In a 2015 interview, Chairman Michel Demaré was asked whether Syngenta could remain independent.
 He responded, "If you have the patience to wait for cycles to materialize, then it would be possible.
But in these circumstances, where our shareholders have a kind of a benchmark share price, what they think this company is worth, it is very difficult to say that we can deliver this in the next twelve months."
 He thereby acknowledged that the company needs to be sold, especially given industry consolidation, which is creating larger competitors.

The failed Monsanto buyout caused Syngenta shares to increase by nearly 40%.
 In February 2016, ChemChina, a Chinese state-owned enterprise, offered to purchase Syngenta for $43 billion (480 Swiss francs per share), a deal which the company "unanimously recommended to shareholders".
 In April 2017, the Federal Trade Commission, the Committee on Foreign Investment in the United States, and the European Commissioner for Competition approved of the acquisition, allowing the largest foreign takeover in Chinese history to proceed.
To secure approval, ChemChina agreed to divest from pesticide production of paraquat, abamectin, and chlorothalonil.
As an additional condition for the acquisition, 67 percent of the shareholders of Syngenta had to offer their shares to ChemChina.
According to a press release, over 80 percent of shareholders agreed to the takeover by May 4, 2017.
The transaction was planned to close on June 7, 2017 and the transaction closed on 26 June 2017.

In November 2017, Syngenta agreed to purchase Nidera from Cofco International.

In March 2018, Syngenta announced plans to acquire Strider, a Brazilian agtech company.
In July, Syngenta acquired Floranova, a flower and vegetable seeds breeder based in the UK.

In September 2019, the company acquired all the assets of The Cropio Gro
Based in Basel, Switzerland, Syngenta was formed in 13 November 2000 by the merger of Novartis Agribusiness and Zeneca Agrochemicals. 
Novartis was formed of the 1996 merger of the three Swiss companies: Geigy, which has roots back to 1758; Sandoz Laboratories which was founded in 1876; and Ciba, founded in 1884. Ciba and Geigy merged in 1971.
Zeneca Agrochemicals was part of AstraZeneca, and formerly of Imperial Chemical Industries. ICI was formed in the UK in 1926. Two years later, work began at the Agricultural Research Station at Jealotts Hill near Bracknell.
In 2004, Syngenta Seeds purchased Garst, the North American corn and soybean business of Advanta, as well as Golden Harvest Seeds. On 5 December 2004,  the European Union ended a six-year moratorium when it approved imports of two varieties of genetically modified corn sold by Monsanto and its Swiss rival, Syngenta.
In 2005, Syngenta opposed a Swiss ban on genetically engineered organisms. On 28 November 2005, Switzerland enacted a five-year ban on the farming of genetically modified crops, underscoring the problems facing the European Commission and biotech companies like Syngenta, Bayer and Monsanto as they try to overcome consumer doubts about safety.
As of 2014 Syngenta's main competitors were Monsanto Company, BASF, Dow AgroSciences, Bayer CropScience and DuPont Pioneer.
In 2014, Monsanto sought to acquire Syngenta for a reported $40 billion, but Syngenta rejected the offer. Since April 2015 Monsanto and Syngenta had been working with their investment banks Morgan Stanley and Goldman Sachs respectively on a deal. The U.S. Treasury tried to stop the deal for tax inversion. Syngenta's Board of Directors rejected an even better offer by Monsanto during August 2015, and Monsanto withdrew from the negotiations on 26 August.
According to the Swiss business weekly, Finanz und Wirtschaft, many Syngenta shareholders were enraged, both by the company's refusal to enter into takeover negotiations with Monsanto, and with the subsequent offer withdrawal. This resulted in a group of investors responding by creating the Alliance of Critical Syngenta Shareholders, which urged the Board to "evaluate all options for value creation without prejudice".
In a 2015 interview, Chairman Michel Demaré was asked whether Syngenta could remain independent.  He responded, "If you have the patience to wait for cycles to materialize, then it would be possible. But in these circumstances, where our shareholders have a kind of a benchmark share price, what they think this company is worth, it is very difficult to say that we can deliver this in the next twelve months."  He thereby acknowledged that the company needs to be sold, especially given industry consolidation, which is creating larger competitors.
The failed Monsanto buyout caused Syngenta shares to increase by nearly 40%.  In February 2016, ChemChina, a Chinese state-owned enterprise, offered to purchase Syngenta for $43 billion (480 Swiss francs per share), a deal which the company "unanimously recommended to shareholders".  In April 2017, the Federal Trade Commission, the Committee on Foreign Investment in the United States, and the European Commissioner for Competition approved of the acquisition, allowing the largest foreign takeover in Chinese history to proceed. To secure approval, ChemChina agreed to divest from pesticide production of paraquat, abamectin, and chlorothalonil. As an additional condition for the acquisition, 67 percent of the shareholders of Syngenta had to offer their shares to ChemChina. According to a press release, over 80 percent of shareholders agreed to the takeover by May 4, 2017. The transaction was planned to close on June 7, 2017 and the transaction closed on 26 June 2017. 
In November 2017, Syngenta agreed to purchase Nidera from Cofco International.
In March 2018, Syngenta announced plans to acquire Strider, a Brazilian agtech company. In July, Syngenta acquired Floranova, a flower and vegetable seeds breeder based in the UK.
In September 2019, the company acquired all the assets of The Cropio Gro
Syngenta