Shareholders have reportedly accepted $128 a share, making the deal worth $66 billion, including debt.
The deal is the largest corporate takeover in almost two decades for a German company.
The latest bid offered by Bayer is 22 percent above Monsanto’s closing price on the New York Stock Exchange on Tuesday.
The acquisition of the leading GMO maker will make Bayer the world’s biggest seed and pesticide producer. The takeover is expected to be closely scrutinized by antitrust regulators.
The deal will potentially leave just a few large global players in the crop and seed industry. American conglomerate DuPont reportedly plans to merge with the Dow Chemical Company and China National Chemical Corporation is set to acquire Swiss agribusiness Syngenta.
Last week, Bayer raised its offer aiming to complete the deal that had been negotiated for more than four months.
Monsanto is as one of the world’s leading manufacturers of genetically modified seeds. The company has long been criticized in Europe, with many consumers skeptical of GMO-derived produce.
Bayer has signed a deal that includes a fee of $2 billion should the transaction fail to get regulatory clearance as planned, a source told Reuters. It should be closed by the end of 2017.
Both companies have so far declined to comment.
Bayer shares extended gains to trade three percent higher on the news.