West Ham will host Juventus for the opening fixture at their new Olympic Stadium home.
The Serie A champions will face Slaven Bilic's side on August 7 in a Betway Cup pre-season match, following a ceremony to celebrate the inaugural match at the ground.
"We are delighted to be marking such a monumental day in West Ham United's history by welcoming one of the world's biggest clubs to our fantastic new home," joint-chairman David Sullivan and David Gold said in a statement.
"It was always our intention to open the new 60,000-capacity stadium on Queen Elizabeth Olympic Park with a fixture fitting of the occasion, and the visit of the reigning Italian champions Juventus is most certainly that.
"We are hugely excited and honoured by this wonderful opening fixture against a historic club which shares many of the values we cherish here at West Ham."
Manager Bilic added: "We hope this will be the first of many games against Europe's top sides at our new home as we begin the journey of turning West Ham United into a team capable of competing with the best teams from across the continent.
"I know my staff and players are very excited about what next season has in store."