Supports money transfer, price comparisons and offers from retailers.
It's downloadable now as an app for iPhone, Android and Blackberry, with a mobile web version available for feature phone users. No iPad or WinPho yet.
O2 has been working on this one for some time, and originally planned to unveil it last year.
The product was delayed thanks to extra stress testing for security and bugs, and in so doing had its thunder stolen slightly by Pingit, the wallet launched by Barclays that also permits person to person money transfer.
That feature - Money Messages - is a central plank of O2 Wallet. Like Pingit, it allows users to load card details and then send money through a simple text to a phone number.
Daily transfers of between £1 and £500 are permitted. O2 is considering charging 15p per text, but for the moment sending money is free.
The ‘My Offers’ service is currently supported by retailers such as Debenhams, Comet, Sainsbury’s Direct, and Tesco Direct.
Meanwhile the price comparison function supports the use of a barcode scanner to check prices and send the user to a price comparison site.
Further features being worked on include the ability to use O2 Wallet to top-up mobile airtime, buy train tickets and make mobile contactless payments via NFC.
The latter would bring the product into line with Orange/Barclays' Simply Tap (which doesn't support money transfer, of course) and Google Wallet (not launched in the UK yet).
Then there's Project Oscar - the cross operator UK NFC project, which is currently subject to approval by the EU. O2 stressed that its wallet is complementary to Oscar because O2 Wallet is a D2C product while Oscar is business-focused.
James Le Brocq, MD at O2 Money, said: “O2 Wallet delivers the benefits of mobile money to more UK consumers than any other product or service currently available.
"With O2 Wallet, it’s easier to transfer money, track expenditure and pay swiftly and securely, all using your mobile. We believe it will transform the way people manage their finances and spend money.”