Tube fares in central London rose by 25% on Sunday.
The fare hikes are designed to cut queues
A single ticket in zone 1 has increased from £1.60 to £2 and bus fares in the outer zones will go up from 70p to £1 for those paying with cash.
But passengers using the Oyster smartcard, which has a pre-pay facility, will be able to travel at 2003 prices.
London mayor Ken Livingstone said the new fares were designed to cut queues at Tube stations and speed up buses by encouraging people to use pre-paid tickets.
The mayor has already revealed a £64m shortfall in his transport budget caused by lower than expected revenues from the congestion charge scheme.
"The new four-year fare package will encourage people to switch to pre-paid tickets like the Oyster smartcard and Bus Saver tickets," said Mr Livingstone last year.
The Tube fare increases include: A zone 1- 2 single rising to 10% from £2 to £2.20
A zone 1-4 weekly travelcard rising by 3.2% from £28.40 to £29.30
A zone 1 weekly travelcard increasing by 12.1% from £16.15 to £18.15
A book of 10 Carnet Tube tickets increasing 30.4% from £11.50 to £15
"London's transport network continues to improve, the most obvious example being the massive improvement of our bus network, but this comes at a cost that has to be met so we can keep the improvements coming."
Customers using the Oyster cards will be able to top them up over the phone, the internet or at ticket offices and machines.
It is hoped that within three years, paying for public transport in London will become a virtually cashless system.
Mr Livingstone also announced that children under 11 will travel for free on all London buses from next year.
And there is also free child travel at weekends with a family travelcard.
He added that any further annual increases will be pegged to inflation.