Dumba delivered a moving speech ahead of Saturday's tilt between the Chicago Blackhawks and Edmonton Oilers and took a knee once the anthem began.
"During this pandemic, something unexpected but long overdue occurred. The world woke up to the existence of systematic racism, and how deeply rooted it is within our society," Dumba said.
"Racism is a man-made creation, and all it does is deteriorate from our collective prosperity. Racism is everywhere, and we need to fight against it. On behalf of the NHL and the Hockey Diversity Alliance, we vow and promise to stand up for justice and fight for what is right."
Dumba, along with current and former NHLers Evander Kane, Akim Aliu, Trevor Daley, Wayne Simmonds, Chris Stewart, and Joel Ward, created the Hockey Diversity Alliance in June to eradicate racism and intolerance in hockey.
The league released a video Saturday with a powerful message from members of the group along with other NHL players and athletes.
Kane criticized the NHL earlier this week for saying the league "has made no effort to support its own Black players."