LONDON—BP PLC has agreed to pay investors $175 million to settle a lawsuit over its disclosure of business risks related to the 2010 Deepwater Horizon blowout, the company said late Thursday.

The disaster, which killed 11 workers, has already forced BP to set aside more than $56 billion to cover cleanup and legal costs. While the settlement removes one source of uncertainty for investors over how much more BP will shell out over the disaster, it also illustrates how, after six years, the spill continues to be a drain on the...