Helaina Trotter was decked out in her pony costume as she walked through her Kingwood neighborhood, the television station reported.
"Helaina hasn't been able to participate in Halloween (for) the last couple of years because she was diagnosed with neuroblastoma on her second birthday," the child's mother, Sarah Trotter, told KPRC.
Helaina spent Halloween getting treatment at a New York City hospital, so she was unable to trick-or-treat with her two older sisters, the television station reported.
"I was really excited because this is going to be the first year doing it and unfortunately she had a reaction to the drug and they put her in ICU," Trotter said.
A family friend, sensing Helaina's disappointment, suggested a Halloween do-over, KPRC reported.
Several neighbors on Helaina’s street took part, passing out candy to the girl when she came knocking.
"It really makes me feel so good about our community that they're doing so much for us because we don't know what's going to happen in the next year," Trotter told KPRC.
The Trotter family has started a GoFundMe page for Helaina.