The controversial London Underground private-public partnership (PPP) plan effectively ended when Transport for London completed the acquisition of maintenance company Tube Lines.
TfL and London Mayor Boris Johnson said the agreement to buy Tube Lines' shares from its shareholders had been concluded, and Tube Lines was now a wholly owned subsidiary of TfL.
Tube Lines was one of the two private maintenance companies responsible for maintaining and upgrading the Underground under a 30-year PPP plan that had been bitterly opposed when introduced in 2003.
Metronet, which was responsible for two thirds of the Tube, went into administration in 2007 with its role being taken over in 2008 by TfL.
Since then, Tube Lines, which has been responsible for the Jubilee, Piccadilly and Northern lines, has been in contractual and financial rows with TfL, with the late-running Jubilee line upgrade a particular bone of contention.
TfL said there will now be an urgent review of the PPP upgrade programmes.
The first priority will be the completion of the Jubilee line upgrade, delivering more frequent and reliable trains as soon as possible.
Mr Johnson said: "This deal opens a new era for the Tube and one that will be free from the complexity and wrangling that hindered us in recent years.
"We have wasted no time in acting to limit the disruption of the Tube upgrade programme by cutting back the closures previously planned for this summer, and we will now look at how we can keep disruption to a minimum in the future."