The millionaire comedian and his 10-year-old son were sitting in his Range Rover when two thugs bashed the driver's window with a hammer, the Daily Mail reports.
McIntyre fell out of the car and appeared to try to fight off the robbers, a witness said. As the thugs fled, the 42-year-old rushed to the passenger side of the vehicle to comfort his son.
The father-of-two, who's worth about $71 million, was forced to hand over his expensive watch in the raid.
Pictures show McIntyre cuddling his son after the terrifying robbery, which happened in Golders Green, northwest London.
McIntyre had just collected his son and was about to set off home when they were attacked at 2pm. He was sitting in the car when the muggers ran up and started bashing the driver's side window. The criminals then demanded he hand over his designer watch.
The witness, who did not want to be named, said: "The guy at the front of the moped started to hit the driver's window about ten to 15 times and it eventually just cracked. He opens the door and gets Michael McIntyre out of the car. Michael fell but he was still trying to put up a fight.
"I just remember one of the bikers trying to get something. I don't know what the guy was trying to get – a watch, a wallet, maybe? And then within seconds they were gone down the hill. It was all so quick – the whole thing must have taken 30 seconds. Michael's son was in the car with him in the front passenger seat."
It's not known if the comedian was targeted or his $227,000 Range Rover was simply in the wrong place at the wrong time.
As crowds of people surrounded him after the attack, McIntyre is said to have shook his head and said: "I need to find out the best thing to do here, I can't say anything."
People living in the area said muggings were common. Residents have learned to hide their phones when they get off the bus for fear of being robbed, the witness said.
The witness said that as the moped riders sped away, McIntyre jumped out of the car to comfort his son while police arrived.
The comedian's agent said McIntyre was "absolutely fine" after the robbery.