Britons lost almost £12.6 billion on gambling last year, a rise of more than a third on five years ago.
Online gambling accounted for almost a third of gambling losses, according to the Gambling Commission, with punters losing £3.63 billion to internet betting and online casino and bingo sites.
A record £1.71bn was spent on fixed-odds betting terminals, which have hit the headlines in recent years over concerns they are highly addictive.
Earlier this year peers called for stakes on the machines - typically electronic games such as black jack, roulette and poker, found in betting shops - to be slashed to help avoid addiction.
Liberal Democrat Lord Clement-Jones said the gaming machines were "destroying lives and damaging communities".
The machines, which allow people to place bets of up to £100 at a time, account for 56% of betting shops' profits, while in-shop betting figures fell.
Campaigners have called for the maximum stake to be reduced to £2, a move which would help reduce "serious harm," deter money laundering and cut betting shop "clustering" on the high street.
While £12.55bn was lost by punters between October 2014 and September 2015, the actual amount bet was higher as the figure only covers betting losses, not the amount staked.
The commission also reported that although almost 200 high-street bookmakers closed, there are still more than 34,700 in towns and cities in Britain.
The number of bingo halls has fallen by more than 10% in a year and there are now fewer than 600, while the amount of money bet at casinos fell to less than £1bn.
But the 147 casino halls were still visited more than 20 million times from October 2014 to September 2015.
The prevalence of arcade machine halls also plummeted, dropping from 1,937 in March 2015 to 1,721 by March 2016.
James Green, from the Gambling Commission, said: "The market share of the online betting, bingo and casino sector is 29% and we'll be interested to see how this varies over time.
"Offline we're seeing changes. For instance, there's been a reduction in the number of betting shops, arcades and bingo halls in the last two years.
"Market trends and consumer participation research are key to shaping the commission's regulatory policy to keep gambling in Britain safe for consumers, fair and crime-free."