O'Brien has been outspoken about the subject since last month's police killing of Houston-native George Floyd.
O'Brien said he would take a knee during the national anthem and that he has always supported his players' right to protest and be heard.
"They’re not taking a knee because they’re against our flag," O'Brien said. "They’re taking a knee because they haven’t been treated equally in this country for over 400 years."
The entire Texans' organization has been vocal about racism since Floyd's May 25 death.
J.J. Watt was the first to speak out publicly about the killing. Then Deshaun Watson, Jacob Martin and other Texans players attended rallies in support of black lives.
Watt, O'Brien, team chairman Cal McNair, his wife Hannah, offensive coordinator Tim Kelly, and defensive coordinator Anthony Weaver were among those who attended Floyd's funeral at Fountain of Praise Church earlier this week.
The Texans have also started a webseries called "Conversations for Change" talking with black former players and coaches about their experiences.
"When you think about how big the issue is, if we can help make a little change in Houston, maybe it’ll be like a pebble in the pond that creates a ripple,” Cal McNair said. "What happened to George Floyd brought to life something that’s bigger than football, and you can’t ignore it. We felt like we couldn’t stay silent. We felt like we had to say and do something. We want to help make changes.
"This is the right thing to do, and I think our players recognize that. We want to support our players and our community. We’re all in this boat together."
"Janice, Cal and Hannah McNair have done an awesome job of listening and having conversations," O’Brien added. “I know they believe in trying to find ways to fight racial injustice in this country. They care so much about this city and the people here, and they care deeply about the players."
O'Brien admits he could have done more in the past to show support, but recent events have opened his eyes.
“I’ve always felt strongly about racial injustice because I was brought up that way,” O’Brien said. “I believe very strongly that white people have to stand with black people in our country.
“Black lives matter. Police brutality is part of it, obviously, but this is so much deeper than that. There are 800,000 policemen and policewomen in this country, and so many of them are trying to do what’s right for their community.
“It’s like what was said at George Floyd’s funeral: It’s about humanity coming together and treating each other as equals.”