Spanish budget airline Clickair, which is in the process of merging with Vueling, is to abandon London Gatwick and transfer all London services to Heathrow.
The airline had previous moved its Bilbao flights to Heathrow ahead of the winter season, but says that its Vigo and Seville links from Gatwick will move from 1 June.
Clickair also operates to La Coruna from Heathrow.
"The decision to streamline all UK Clickair flights is designed to provide an improved service for passengers," says the airline.
Last year it carried 316,000 passengers between London and five Spanish cities - which included Valencia - but hopes to exceed 400,000 this year with the switch to Heathrow.