Players from both clubs wore T-shirts saying Black Lives Matter during batting practice, and the letters "BLM" were stenciled into the back of the mound at the center of the diamond.
The Yankees won the rain-shortened game 4-1.
A Black Lives Matter stencil will appear on pitcher's mound across the majors during the opening weekend. Los Angeles Dodgers star Mookie Betts and some San Francisco Giants players also kneeled during the national anthem before their game.