Izetta Scott, 69, was charged with leaving the scene of an accident with injury.
The boy was taken to Le Bonheur Children's Hospital in Memphis. Police said his arm had been broken in two places.
Police said the 5-year-old, along with his 15-year-old sister and a 17-year-old boy, were crossing Plaza Avenue at North Ninth Street just after 6 p.m.
The child's older sister told police that a black car came speeding down the street and struck the boy.
She said two ladies in the car stopped and asked if the child was OK, then drove off. The sister remembered their license plate number, however, and told police.
Around 6:30, officers were called to the intersection and found the 5-year-old with apparent injuries to his arm and tire marks on his shirt.
Helena-West Helena police traced the tag number to Scott, who told officers that she saw a young man, a young woman and the child in the median of the street.
Scott told police the child darted into the street and ran into the side of her car. When she asked if he was OK, the young man picked the child up and said, "It's OK," before the three continued walking, so she drove home.
The child lives off Ninth Street. A man who said he is the child's uncle didn't want to go on camera, but said he's glad the boy is going to recover.
Scott was released on her own recognizance due to her age and health issues, police said. The accident is under investigation.