Michael O'Leary, chief executive of the Dublin-based carrier, said the number of booking options for bags will be slashed from 108 to just six.
The no-frills airline currently charges different fees for each checked-in bag depending on whether it weighs up to 15kg or 20kg, whether it is the passenger's first or second bag, and whether the flight is in high or low season.
O'Leary said a flat fee of "probably £30" will be introduced for bags.
This would represent a 50% increase on the existing £20 online price of checking in a 15kg bag during the low season.
It currently costs £40 to put a 20kg case in the hold during the high season.
The "vast majority" of passengers who check bags in do so in the high season, meaning they will pay a lower price, Mr O'Leary said.
He told reporters that the proportion of travellers checking in bags rises to 30-35% during the summer and falls to as low as 5% in November.
The Ryanair boss denied that the change in policy was an acknowledgement that the airline has previously unfairly penalised families who check in bags for their summer holidays.
"Families, like everybody else, are travelling with less checked bags," Mr O'Leary said.
"The purpose of the bag fee was never to penalise people. It was to incentivise people to travel with less checked bags."
Passengers will still have to pay higher baggage fees for longer flights, such as London to the Canary Islands, and for some domestic flights in countries such as Spain and Italy.
The announcement was made as Ryanair unveiled its plans for the third year of its customer experience improvement programme, Always Getting Better.
The measures include enhancing its mobile app, enabling passengers to leave feedback on flights, and introducing a new fare to give extra benefits to leisure passengers.
O'Leary said the initiative has resulted in a "fundamental change" to the way Ryanair treats customers.
"My approach was, you're getting the lowest fare, an on-time flight, we won't cancel and we won't lose your bags. Now shut up, sit down and don't complain," he explained.
"That's been transformed."
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