The Tube will run later at weekends from May 2007, the mayor has announced.
Many Londoners said they would like late running trains
Ken Livingstone said the London Underground would run until 0100 on Friday and Saturday nights - 30 minutes later than current timetables.
There will also be change for morning services, with trains running from 0630 rather than 0530 on Saturdays.
A passengers' watchdog has called for alternative transport to be laid on for Saturday morning workers affected by later running services.
Sunday morning services will remain unchanged, beginning at 0700.
Original London Underground (LU) plans to run Tube trains an hour later on Fridays and Saturdays were changed to try to ease weekend workers' fears.
The proposals raised fears that shift workers and those catching flights from Heathrow would be affected.
The time changes came after a public consultation which attracted 54,000 responses - most of which favoured a later weekend Tube service.
Making the announcement on Friday, Mr Livingstone said: "We know that the majority of Londoners would like the Tube to run later at weekends so they can travel home safely after a night out at the theatre or a club.
"A significant minority rely on the Underground to get to work early on Saturday and Sunday mornings.
"This package ensures the Tube runs later on Friday and Saturday nights whilst protecting the needs of early morning commuters."
Brian Cooke, chairman of passenger group London TravelWatch, said the new hours were an improvement on the original proposal.
But he said he remained concerned that passengers who rely on the Tube in the morning, such as cleaning and retail staff, NHS workers and travellers heading for airports, will not be provided for unless alternative transport is introduced.
Justin Bowden, the GMB union's senior London organiser, said there should be consultations over the impact of the changes on workers.
"It is not right to rob Peter of his train to take him to work to enable Paul to socialise later at the weekend. Both demands need to be accommodated," he said.
Richard Parry, of LU, said the changed timetable would help to boost London's late-night economy.
LU said staffing levels will remain the same in the final hour.
It is also working with British Transport Police to ensure enough officers are available to police the Tube.