The German company, which owns agriculture giant Monsanto, says herbicides containing glyphosate are safe.
On Friday, Monsanto was ordered to pay $289m (£226m) damages to a man who claimed the products caused his cancer.
A Californian jury said Monsanto should have warned users about the dangers of its Roundup and RangerPro weedkillers.
Bayer completed its $66bn takeover of Monsanto in June.
A Bayer spokesperson told the BBC the two companies operate independently.
The landmark lawsuit was the first to go to trial alleging a glyphosate link to cancer.
The claimant, groundsman Dewayne Johnson, was diagnosed with non-Hodgkin's lymphoma in 2014. His lawyers said he regularly used a form of RangerPro while working at a school in Benicia, California.
He is among more than 5,000 similar plaintiffs across the US.
Glyphosate is the world's most common weedkiller. The California ruling could lead to hundreds of other claims against Monsanto.
The company said it intends to appeal against the verdict.