Ryanair has said many customers will no longer be able to take two pieces of luggage into the cabin.
The budget airline said passengers without priority boarding would have to put their second bag in the hold free of charge at the gate.
For bigger bags Ryanair is cutting fees from £35 to £25 to encourage customers to check in more luggage.
Ryanair said it was making the changes from November to ease delays after too many customers took two bags on board.
The airline said earlier this year it was a victim of its own "niceness" after allowing customers to bring a second carry-on bag for free.
It said "abuse" of that policy was contributing to flight delays, with people taking on bags up to three times the permissible size.
Under the changes announced on Wednesday, Ryanair passengers without priority boarding will only be able to take one smaller carry-on bag on board the aircraft.
At the same time it is lowering checked-bag fees and increasing the check-in bag allowance from 15kg to 20kg.
Analysis: By Richard Westcott, Transport Correspondent
Put simply, from November, Ryanair won't let you bring your wheelie bag into the cabin any more, unless you pay to be a priority boarder.
But you'll still have to carry that bag through security, which means you still can't pack razors, liquids etc. They then take it off you at the gate, for free.
Ryanair makes money by filling its planes and minimising delays on the ground.
But full planes don't have enough space for everyone to have a wheelie bag, which leads to that big, time-consuming bun fight before every flight where the late boarders are looking for bag space.
By changing the policy, Ryanair will cut delays and save money. That keeps fares down, but it means you'll have your own delay, waiting for your bag to come around the carousel at the other end.
Ryanair chief marketing officer Kenny Jacobs, said: "These bag policy changes will cost Ryanair over 50m euros (£46m) per annum in reduced checked bag fees.
"However, we believe offering bigger bags at reduced fees will encourage more customers to consider checking-in a bag, which will reduce the high volume of customers we have with two carry-on bags at the boarding gates."
How much will I pay for baggage?
The range of fees for putting baggage in the hold is so varied that some airlines produce hefty tables detailing the various charges.
The cost depends on the date of departure, the route, and the ticket type, as well as the obvious elements such as the size of the luggage.
Travel with equipment such as golf clubs brings additional costs. Most airlines charge a lot more than the prices below for baggage that is checked-in at the airport rather than online.
The major competitors to Ryanair include:
- easyJet - charges between £13 and £30 for hold luggage up to 20kg
- Wizz Air - charges between 16 euros (£15) and 55 euros for hold luggage up to 20kg
- Norwegian - various charges ranging from £7 to £50 for the first piece of hold luggage
- British Airways - free luggage allowance on some tickets, but on basic fares can range from £20 to £60
Ryanair carried nearly 13 million customers in August, 10% more than a year ago, and its planes were 97% full.
It flew 126 million passengers in the 12 months to the end of August, a rise of 13%.
The airline reported a 55% increase in pre-tax profits to 397m euros (£356m) in its most recent quarter.
Rival easyJet said on Wednesday that it carried 8 million passengers last month, a rise of 9%.
Shares in Ryanair and easyJet both fell nearly 1% in London.