Jurors found on Friday that the company had acted with "malice" and that its weedkillers contributed "substantially" to Johnson's terminal illness.
Nearly after three days had past of the deliberations in this week, the jury of the Supreme Court of California located in San Francisco, awarded Dewayne Johnson a huge amount of $250 million were awarded for the punitive damage caused and the other $39 million for the compensatory damages.
Monsanto is now owned by German chemicals and pharmaceuticals major Bayer, after it successfully completed the acquisition on 7 June 2018 following the receipt of all required approvals from regulatory authorities.
Several North Texans have also sued Monsanto claiming Roundup caused them to get sick.
While observers predicted thousands of potential future claims against the company in the wake of Monsanto's defeat, Bayer - which recently acquired the USA giant - said the California ruling went against scientific evidence.
The company has denied ties between glyphosate, the active ingredient in Roundup, and cancer.
Pedestrians hurt as car hits barrier at #Westminster
He then abandoned his vehicle and broke into a courtyard at the Houses of Parliament where he stabbed and killed PC Keith Palmer. A man was arrested after the auto smashed into barriers outside the parliament building. "It looked deliberate.
"The verdict today, it doesn't change the overwhelming scientific evidence and the 40 years of safe use of glyphosate around the world", said Scott Partridge, Vice-President of Monsanto.
Monsanto issued a statement saying that scientific studies and reviews "support the fact that glyphosate does not cause cancer".
A California jury has decided that Monsanto knew about the health hazards of its Roundup weed killer when it was used by 37-year-old Dewayne Johnson.
"He said: "'It's taken a lot of prayer, I've taken energy from a lot of people. Jurors awarded him $39 million for his losses and $250 million to punish the company after finding it liable for a design defect and failing to warn of Roundup's risks. The latest annual report of Monsanto's India unit states that its brand Roundup maintains market leadership with sales of around Rs 185.66 crore, which is 28 percent of its net sales of Rs 667.44 crore in FY18.Roundup is primarily used in agriculture and places like roadsides, public spaces, railway tracks and gardens. One man in particular, Dewayne Johnson brought the fight to highest courts, because he evidently had very little to lose. "It's just a matter of time", Mr Wisner told the jury in his opening statement last month.
Two years later, in 2014, he was diagnosed with non-Hodgkin's lymphoma. It was acquired by Bayer for more than $62 billion in June.
Monsanto attempted to defend itself by relying on broad-based studies that have shown glyphosate exposure to have little or no effect on users.
The worldwide agricultural company continues to insist that glyphosate, the active ingredient in herbicides like Roundup and Ranger Pro, are safe at any level.
The company began genetically modifying plants, making some resistant to Roundup.