The Luton-based firm said its load factor – a measure of how full its planes are – stood at 86.9%, marginally ahead of the same month last year.
EasyJet offered up to 20% off 2m seats between June 16 and July 17, following a similar promotion for May and June, as competition in the sector intensified in the face of weaker consumer spending.
Issuing statistics for June, easyJet said it carried 4.11m passengers last month, an increase of 19.5% on a year earlier. The figure benefited from the acquisition of GB Airways from British Airways at the start of this year.
The company also said revenues per seat continued to improve and that nearly 70% of the seats available for the second half of the year had been sold.
Operators such as easyJet are fighting to fill their planes at a time when the industry face soaring oil prices.
Rival Ryanair recently stepped up the pressure by offering 250,000 one-way seats for £10.
British Airways showed the impact of the difficult environment when it said on Thursday that it carried 2.91m passengers in June – 2.9% down on June, 2007. BA planes were 76.7% full in June, compared with 80.5% in June last year.
Three airlines have so far gone bust as a result of the soaring costs – Silverjet called in administrators last month after the demise of Stansted to US all-business class carriers Eos and MAXjet.