The California jury's decision marks the largest award yet in a string of lawsuits that claim the firm did not adequately warn about cancer risks from talc-based products.
A spokeswoman for Johnson & Johnson defended the products' safety.
The firm plans to appeal, as it has in previous cases.
"We will appeal today's verdict because we are guided by the science," Carol Goodrich, spokesperson for Johnson & Johnson Consumer Inc, said in a statement.
The evidence around any link between talc use and cancer is inconclusive.
Johnson & Johnson, headquartered in New Jersey, faces thousands of claims from women who say they developed cancer due to using the firm's products to address concerns about vaginal odour and moisture.
Johnson & Johnson has lost four of five previous cases tried before juries in Missouri, which have led to more than $300m in penalties.
The California lawsuit was brought by Eva Echeverria, a 63-year-old woman who said she started using baby powder when she was 11 years old. She was diagnosed with ovarian cancer 10 years ago; the diagnosis is terminal, according to lawyers working on the case.
The lawsuit alleged that the company was aware of cancer risk associated with talcum powder, but concealed that information from the public.
The verdict included $70m in compensatory damages and $347m in punitive damages.