CE is privately owned, but is backed by investors including Bill Gates, Murray Edwards, Oxy Low Carbon Ventures, and Chevron Technology Ventures.
It is unclear what BHP's stake will be in the company.
CE CEO Steve Oldham welcomed BHP's investment.
"At CE we're focused on commercialising technologies that can play a critical role in addressing climate change," he said.
"As we work to deploy our technologies at large scale around the world, we're thrilled to welcome investment from industry-leading companies like BHP."
"BHP's global reach and experience in executing complex projects, as well as their strategic commitment to reducing emissions, make them an ideal partner to help us accelerate the commercialisation and use of CE's technologies.
"We're looking forward to working with BHP and our other partners as we progress the development of DAC and Air to Fuels facilities, and ultimately achieve our goal of delivering affordable, carbon-neutral fuels and significant emissions reductions around the globe."
BHP vice president, sustainability and climate change Dr Fiona Wild said BHP was committed to accelerating the global response to climate change by investing in emerging technologies that had the potential to lead to material reductions in greenhouse gas emissions.
"As the Intergovernmental Panel on Climate Change (IPCC) stated in late 2018, if we are to avoid the worst effects of climate change, technologies that capture and remove CO2 will be required," she said. Direct Air Capture offers flexibility and potential, and could play a vital role in reducing future global emissions.
"We hope that this investment can accelerate the development and adoption of this technology.
"We know that investing in emerging technologies to reduce emissions is just one part of addressing climate change.
"At BHP, we also set greenhouse gas emissions reduction targets for our operations, we build the resilience of our operations and communities to the physical impacts of climate change and we work in partnership with our resource sector peers to improve sectoral performance."
Wild said the investment in CE complemented BHP's existing efforts to accelerate the development of carbon capture, utilisation and storage (CCUS) at point sources of CO2 emissions, such as in steel-making and power generation.
"Government support for technologies that capture carbon has been important," she said.
"However mobilising private capital and supporting market mechanisms to finance technologies that address global emissions will be critical if we are to build a net-zero emissions economy. This investment is a good example of the role that the private sector can play in bringing such technologies to market."