Wylie police said investigators have identified the boy known as "Wylie's Angel."
A landscaper found the boy's body abandoned in a park near Lake Lavon on April 15.
Wylie police said the boy was identified as 6-year-old Gerren Joseph Isgrigg.
Police arrested Darlene Phillips, 63, in the child's death late Friday night.
Detective Venece Perepiczka said the case is still under investigation, but authorities do have enough to charge Phillips with murder.
"Circumstances that she was in control of led to his murder," she said.
Investigators said Phillips was the child's primary caregiver.
Perepiczka declined to say where Phillips resides.
Wylie police said a tip from the National Center for Missing and Exploited Children led to the child's identity. Investigators had received hundreds of tips in the case.
Police released a photo of the boy from the boy's father that was taken about three years ago.
Investigators have spoken to the child's biological parents, who are not married and live in separate states outside of Texas. The father, who lives in Oklahoma, and the mother, who lives in California, are not considered suspects in the case, Perepiczka said.
The medical examiner earlier said the child appeared to have had severe medical needs and was fed at some point through a feeding tube. The cause of death has not been determined, but the medical examiner said there were no signs of physical trauma.
Now that boy's identity is known, the medical examiner's office can look at his medical history and determine a cause of death. Perepiczka said Friday that the boy's body had no apparent trauma.
"This was just a very unfortunate circumstance in a situation where this little Gerren was not taken care of well, and it ended up to his murder," she said. "That's that best way that I can describe that right now."
Autopsy results were still pending Friday night.
Wylie residents have held vigils to pray for Isgrigg and have left teddy bears and other stuffed animals at a memorial at Eastfork Park, where the boy was found. Volunteers passed out fliers about the boy, and a North Texas woman set up a Facebook page to raise awareness of the case.
"The effort that the media and that the public put into this definitely led to the positive identification of Gerren," Perepiczka said. "At the end of the day, I think the best thing that we did was identify Gerren and find who was responsible for his untimely demise."
Phillips is being held in the Collin County Detention Facility on a $500,000 bond.