The Airbus A340 was a few minutes into its journey to New York's JFK airport when it reported the incident. However it continued on across Ireland before deciding to return.
A recording of one of the pilots of flight VS025 requesting permission to return was published online.
He used the code "pan, pan, pan" to alert air traffic control to an onboard emergency that does not pose a threat to life.
"We have a medical issue with one of the pilots after a laser incident after take off and we are going to return to Heathrow," says the pilot.
The air traffic controller confirms the route and then returns to the radio to ask for more details of the incident.
A spokeswoman for Virgin Atlantic said the flight landed safely and the airline was now working with the authorities to identify the source of the laser.
"The VS025 travelling from London Heathrow to New York JFK flight has returned to Heathrow as a precautionary measure due to a laser beam incident," she said.
"The safety of our crew and customers is our top priority and we apologise for any inconvenience to those onboard.
All customers will be offered overnight accommodation and we will get them on their journey as soon as possible."