Costner, 55, spent weeks calling attention to the high-tech machine developed by his company saying it could help in cleaning up the gulf oil spill, ABC News reported.
After testing the device, BP released a statement saying that it works and company officials are "excited" about its potential.
"We were confident the technology would work but we needed to test it at the extremes," Doug Suttles, BP's chief operating officer, said.
Suttles said BP has placed a significant order with Costner's company, Ocean Therapy Solutions, and will be working with the firm to rapidly deploy 32 of the machines.
The device is a centrifuge that separates spilled oil from water.
Costner spent more than $20 million developing the oil separator that testing indicates leaves water 99 percent free of oil.