Speaking to CNN's Chris Cuomo with Castile's family and her lawyer by her side, Reynolds recounted the moment Castile was pulled over for a broken tail light -- an encounter that ended in his death.
She said now she is fighting for all of the families that have lost loved ones.
"I just want justice for everyone," she said. "Everyone around the world. Not just for my boyfriend and the good man that he was."
The interview comes just hours after a peaceful protest in Dallas -- inspired by the death of Castile and the fatal police shooting of Alton Sterling
in Louisiana -- was interrupted by gunfire that left five officers dead
. Reynolds says that she believes that the shooting "was not because of something that transpired in Minnesota," and Castile's mother Valerie said she's been too preoccupied dealing with her son's death to follow the news.
"This is bigger than Philando. This is bigger than Trayvon Martin. This is bigger than Sandra Bland. This is bigger than all of us."
Reynolds sought to clarify what happened before the live stream began Wednesday, saying the officer only asked if they knew why they were being pulled over and if they had licenses and registration. She says Castile complied.
"He absolutely did everything that the police asked him to do up until he was killed."
The family said they still have not seen Castile's body, but expect to be able to later Friday. They also called for an independent investigation into the incident.
Perhaps the most upsetting part of this story is the involvement of Reynolds' four-year-old daughter. She was in the car when Castile was shot, and could later be heard on the live stream, trying to comfort her mother. Friday, she was set to graduate from pre-school, an event that Castile, a father figure to the girl, planned to attend.
"I'm going to be strong, but it's my daughter that has to live with this on her little brain for the rest of her life," Reynolds said.