The firm, owned by Spanish telecoms giant Telefonica, had been awaiting the outcome of a radio spectrum sale originally set for later this year, but the auction has been knocked back into 2018 following a legal challenge from rival operators.
Telefonica is understood to have wanted the auction out of the way before triggering the initial public offering (IPO) to prevent any uncertainty dogging its potential.
While the operator made no firm commitment to float this year, it was deemed possible that an IPO could be launched if market volatility subsided and the airwaves auction went ahead as planned.
Telefonica has been eyeing a cash-raising on O2 as a means of driving down its £42.7bn debt pile.
However, the need to float the British mobile network to generate funds is now less pressing, with the Spanish group seeing its cash flow strengthen.
Telefonica revealed that it would explore a London-listing of O2 in September 2016 after seeing a tie-up with rival operator Three collapse.
The European Commission had formally blocked Hong Kong-based mobile operator CK Hutchison, which owns Three, from pushing through a £10.3bn takeover of O2 in May last year.
Despite hopes of getting the IPO off the ground in 2016, Telefonica has paused until this year, with the airwaves auction a factor in when to push the button.
Ofcom revealed the rules for the mobile spectrum auction in July as it looked to meet the insatiable demand for data from UK smartphone users.
The telecoms regulator said the auction would support 5G mobile and increase the available airwaves for mobile devices by a third. It plans to auction licences in two frequency bands.