It happened just before 6pm Saturday at the Trails at Dominion Park Apartments in the 200 block of Dominion Park Drive.
According to witnesses, the apartment complex swimming pool was crowded with kids when the boy went under water.
Officials said another child spotted the boy at the bottom of the pool.
The child pulled the boy out and he managed to take a few breaths before being rushed to Houston Northwest Medical Center where he died from his injuries.
It's unclear whether adults were outside at the time.
CPS spokeswoman Gwen Carter tells Eyewitness News they are investigating the child's death. No other details were released.