The recently re-launched Cosmos, who have just added former Spain international Marcos Senna to their side, are preparing to begin life in the North American Soccer League.
And this fixture, taking place at Brisbane Road on Wednesday July 24 at 7:30pm will replace Orient's planned friendly with Aldershot.
"We are delighted to be hosting the Cosmos and look forward to welcoming them and their followers," O's chief executive Matt Porter told the club's official website.
"This is the latest in a line of exciting announcement this summer and a rare opportunity to see the O's take on opponents from across the Atlantic so we are hoping for a great turnout in E10."
- Sports & Recreation