Ryanair is cutting its check-in time window from four days to 48 hours for passengers without reserved seats.
It said the changes to online check-in would take effect from 13 June.
Ryanair said that even after the change, the check-in window was still double that of many of its rivals.
The airline said the move will give customers who have paid for reserved seating more time to pick their seats. Those customers will be allowed to check-in up to 60 days before flying.
Seat allocation has become a hot topic for air passengers who suspect airlines of deliberately splitting up family groups in order to try to get them to pay for seats together.
Ryanair has come under heavy criticism for its customer service in the past. The airline is now in the fifth year of its “Always Getting Better” customer service improvement programme.
The carrier’s last main change for flyers was to introduce a £5 fee for priority boarding, without that they risked having their main cabin bag being put into the hold at the gate.
That move was delayed after the airline had to cancel hundreds of flights resulting from a rota change and a shortage of pilots.
Ryanair was also hit by a series of industrial actions across Europe in protest at pay, conditions and union recognition, also added to the disruption.
More action is threatened by European unions this summer unless Ryanair adopts national employment laws for all their workers.