The 24-hour weekend service on the Jubilee, Victoria and most of the Piccadilly, Central and Northern lines in London was due to start on 12 September.
Tube workers staged two 24-hour strikes in July and August in a dispute with London Underground (LU) over rotas and working conditions on the new service.
LU said it had deferred the introduction to “allow more time” for talks with the unions.
LU managing director Nick Brown said: “Further to the progress made in recent days with the trade unions and the suspension of strike action, we believe we are not far from an agreement that protects the work-life balance of our employees and is affordable, sustainable and fair.
“As such, we have decided to defer the introduction of Night Tube to allow more time for those talks to conclude.
“Our objective is to reach an agreement that ends this dispute and delivers the Night Tube for Londoners this autumn.”
London Mayor Boris Johnson said: “As I’ve previously made clear, I’m not interested in a staring match over 12 September and I want to see night Tube introduced this autumn.
“Agreement on this is in everyone’s interests – Londoners, businesses, visitors to our city and the hard-working London Underground staff who are central to making this happen.”
He added further strike action “isn’t going to benefit anyone”.
Mick Whelan, general secretary of Aslef, welcomed the deferral of the launch.
He said: “It has to be done in a way that works for London Underground, for passengers, and also for the drivers who deliver this service every day.
“Had LU not acted in bad faith, by trying to introduce the Night Tube in London without consultation, and without negotiation, we wouldn’t be where we are today and they would have been in a position to deliver.”
However, the RMT has set two new Tube strike dates of 8 and 10 September if no agreement reached.
RMT general secretary Mick Cash said: “RMT welcomes this move, which is what we have been calling for ever since we went into dispute over the night Tube issue.
“We warned repeatedly that it would be dangerous and foolish to press ahead with bodged night Tube plans until the very basics in terms of staffing and safety had been agreed with the unions through the long-established frameworks.”
The RMT added the move mean its members were “right to strike”.
Businesses expressed dismay at the deferral.
David Leam, of business group London First, said: “This is disappointing for businesses, but if it gives London Underground and the unions time to come up with a long-term deal it will be worth it.”
In September 2014, TfL announced the Night Tube would run on Fridays and Saturdays with six trains per hour through central London on five Tube lines, while on the Northern Line, there would have been eight trains an hour to meet demand at busy stations between Leicester Square and Camden Town. This would bring new lease into the entertainment and night life of Londoners who frequent areas such as North Woolwich with the O2 and Indigo arenas – homes of many late finishing big ticket concerts and performances – the West End areas of Piccadilly, Leicester Square, Soho, Chinatown and Trafalgar Square – the hub of London’s night life.
Chancellor George Osborne and Mr Johnson said it would add £6.4bn to the London economy by 2030 and create 500,000 new jobs.
Story from BBC News