Samuel Olson, 6, was last seen Thursday in the 8800 block of McAvoy Drive.
Samuel is white, 3 feet 9 inches tall and weighs 50 pounds. He has blue eyes and light brown hair.
He was last seen wearing a gray T-shirt with a red "Kool-Aid man" on the front, jean shorts and white "Buzz Lightyear" tennis shoes.
Tanya Olson, Samuel's grandmother, told ABC13 he's missing two bottom teeth and another tooth was loose.
Samuel turned 6 years old over the weekend, his grandmother said.
Samuel was in the care of a relative of his father's fiancée when his mother, who doesn't have custody, appeared with someone claiming to be a police officer and demanded to take the boy, Tanya said.
"We found out the police officer wasn't real," Tanya told ABC13.
If you have any information about this disappearance, call 911 or the Houston Police Department Missing Persons Unit at 832-394-1840.