Operations will "run smoothly" and there will be "no flight cancellations" during the period of industrial action from 25-27 May, the airport said.
It comes as Heathrow urges the Unite union to put its pay offer of a 10% pay increase, a £1,150 lump sum for 2023 and inflation-linked increase for 2024 to their members.
Heathrow chief executive John Holland-Kaye said: "Passengers should not be concerned about strike action by Unite over the half-term getaway.
