The agreement will bring a European contribution to the spacecraft's Exploration Mission-1 set for 2017, NASA reported Wednesday.
The Orion vehicle has three major components -- the four-man crew capsule, the launch abort system, which would pull the crew module to safety in the unlikely event of a life-threatening problem during launch, and the service module, which will house Orion's power, thermal and in-space propulsion systems.
That's the component the ESA will provide under the terms of the agreement signed in med-December, NASA said.
"This is not a simple system," Orion Program Manager Mark Geyer said. "ESA's contribution is going to be critical to the success of Orion's 2017 mission."
That mission will be the first integrated flight test of both the Orion spacecraft and NASA's new Space Launch System rocket.
"We have a lot to look forward to in the coming years with human exploration," said Dan Dumbacher, deputy associate administrator for Exploration System Development at NASA Headquarters in Washington. "NASA is thrilled to have ESA as a partner as we set out to explore our solar system."