Budget carrier easyJet has put more than 145,000 extra seats on sale this summer between the UK and amber list countries.
It includes destinations such as Spain, Greece, Portugal, France, Italy, Croatia and Cyprus, with fares starting at £22.99 per person, one-way.
The airline is operating around five million seats on flights between the UK and 85 green and amber list locations across Europe this summer.
Johan Lundgren, easyJet chief executive, said he was "delighted" with the customer response to the removal of amber list quarantining for the fully vaccinated.
"We have always said that vaccination is the key to unlocking travel and this means that millions will finally be able to reunite with family and loved ones abroad or take that long-awaited trip this summer," he added.
"We urge the government to remove expensive testing for fully vaccinated people travelling to low-risk green and amber destinations as we do not want to see a return to flying being a preserve of the rich. We look forward to playing our part in getting the country flying again this summer."