Marc Gilbert was washing up in the kitchen of the family's home in Houston, Texas, when he heard a noise coming from their two-year-old daughter Allyson's room.
He realised the noise was coming from the monitor, and heard a stranger's voice calling his little girl an
'effing moron' and 'little slut'. Horrified, Marc disconnected the device – which also had a camera attached to it - from the mains.
Mr Gilbert said he believes the hacker infiltrated the monitor via the family's internet router, and could see little Allyson in her bed – and knew her name because it was written on the wall above her head.
"He said, 'Wake up Allyson, you little (expletive),'" the outraged dad told ABC News.
"I see the camera move on us, at that point I ran over and disconnected it and tried to figure out what happened."
The worried dad-of-two did some research and is now convinced that the monitor was accessed via his internet connection.
"[I] couldn't see the guy. All you could do was hear his voice and he was controlling the camera," he said, adding that the man had a British or European accent.
The family are now worried that their daughter's room could have been watched before without them knowing.
"It's quite possible that this had been going on more than one day," Marc said. "Security vulnerabilities exist."
Marc added that little Allyson would not have heard the man's vile insults as although she has a cochlear implant, she is deaf.
Marc, who is also dad to three-year-old Ethan says he will never use a monitor again.