Wizz Air said it carried 833,000 passengers, compared to 126,549 a year prior. Ryanair said it operated over 12,000 flights in May, carrying 1.8 million passengers onboard, up from just 70,000 in May 2020.
It also confirmed it has increased the number of aircraft seats across its network to 1.3 million a week.
Shares in Ryanair ticked up about 0.1% on Wednesday.
Meanwhile, Wizz Air also said it has added a "record number of routes ever announced at one time".
"Some 50 routes have been added to the schedule, including the addition of Abu Dhabi," said Susannah Streeter, senior investment and markets analyst, Hargreaves Lansdown.
"Expansion into the UAE is a key part of its plan with the airline aiming to replicate the success of its Wizz Air Hungary in the Middle East."
However, it's not all good news, with Wizz's revenue taking a major hit. It has warned of even more losses going forward as the pandemic continues to take a toll on the travel industry.
Wizz shares were down about 1.6% on Wednesday morning.
The UK has introduced a "traffic light" system for travel, where countries are divided into green, amber and red. Britons traveling to green list nations don’t need to quarantine when they return to the UK unless the COVID-19 test they take on or before day two after their return is positive.
Despite calls by the industry to expand the list, UK prime minister Boris Johnson said last month: "I don't expect that we'll be adding to it very rapidly and indeed we will be maintaining a very, very tough border regime for the foreseeable future."
Ryanair chief Michael O’Leary told Sky News that the UK must add Italy, Spain and Greece to its green list, given "the vaccination programme is now stopping transmission."
Meanwhile, the European Commission has proposed that vaccinated people should be exempt from testing or quarantines when traveling from one EU country to another, and the EU is also welcoming vaccinated tourists.
Watch: Ryanair boss hits out over coronavirus 'scariants' and calls for travel to EU and US to open up