The app includes listings, Time Out Critics Choice picks and editorial features and is updated daily to ensure that users get the inside track on what’s happening in the capital.
The launch comes as Time Out considers plans to convert its 55,000 circulation paid-for weekly into a free title and follows the successful launch of a free New York edition iPad app in April.
Asked whether launching a free iPad app indicated the print title would be going free, Carolyn Sims, marketing director of Time Out, told Media Week that move was merely a progression of the other free apps that the title has rolled out recently. She confirmed the app would be free "for the foreseeable future".
Time Out claims the London app's intelligent personalisation functionality learns user preferences over time to generate personalised recommendations based on their previous choices and those of similar users.
Users can search events and attractions by date, event type and location, and share grouped lists online.
In the coming weeks users will be able to instantly book restaurants and events including unique MasterCard Priceless London experiences via the app.
The MasterCard sponsorship, the value of which was not disclosed, was negotiated by its media agency Universal McCann.
David Pepper, chief commercial officer of Time Out, said: "The business has been delivering strong traffic online and achieving 70% digital revenue growth year-on-year, a great platform from which to launch the app for our London consumers.
"We are particularly proud of the enhanced user experience the app offers our consumers, demonstrated by the success of the recently launched New York edition. We will be launching city editions from across our portfolio in the coming months."
Paul Trueman, head of marketing for MasterCard in the UK and Ireland, said: "Our long term partnership with Time Out is evolving with the smart use of technology to help consumers unlock the best experiences throughout London."
Time Out is planning to launch a Paris edition iPad app, with other countries planned to follow.
Although MasterCard is the main advertising partner for the launch, the app will be carrying other advertisers following the initial phase.Follow @nickbatten2