Cassidy Stay, 15, was released from Children's Memorial Hermann Hospital after being admitted Friday for a gunshot injury to the head.
The rest of her immediate family — 39-year-old father Stephen Stay, 34-year-old mother Katie Stay, and siblings Bryan, 13, Emily, 9, Rebecca, 7, and Zach, 4 — died in the massacre.
Ronald Lee Haskell, Cassidy's former uncle, is accused of shooting the family Wednesday in their home while allegedly trying to find out the whereabouts of his estranged wife, Rebecca Stay's sister, Melannie Haskell.
Cassidy is expected to make a full recovery from her injury.
Her relatives "thanked the community, both here in Houston and all over the country, for the outpouring of love and support they have received these past several days," the hospital said.
Ronald Haskell has been charged with capital murder.