The manager has confirmed that Manchester United's record signing will feature against Burnley on Saturday but that Marcos Rojo will have to sit out.
The Argentina international moved to Old Trafford in a deal worth €75 million from Real Madrid on Tuesday, becoming United's fourth senior signing this summer.
Van Gaal confirmed that Di Maria has immediately become part of his plans for Saturday's visit to Turf Moor as he seeks his first Premier League victory.
"I think he is ready to play," the Dutchman told MUTV.
Fellow Argentine arrival Marcos Rojo, however, is not ready to make his first appearance in a United shirt as he continues to wait on a valid work permit.
"It's only a matter of time," Van Gaal said. "I'm the manager of the biggest club in the world, but I can't change the law!"
Manchester United have started the season in woeful fashion. Before being eliminated from the Capital One Cup to a third division side, they opened their Premier League campaign with a loss and a draw.