A relaxation of the rules will allow gaming operators to join the National Lottery on TV from September next year, as long as their ads are deemed to be "socially responsible".
Gambling promotions must not target children or suggest that betting can lead to sexual success or enhance attractiveness. Nor will they be allowed to portray gambling as an answer to financial problems.
The Advertising Standards Authority will enforce the rules with Ofcom and the Gambling Commission.
Advertising for spread betting will also be permitted, although only on specialist financial TV channels.
The boss of an advertising agency whose clients include a major gaming operator said: "Gambling is a massive growth area with huge pent-up demand. As the restrict-ions are lifted, I would expect operators to invest heavily in TV advertising."
At present Ladbrokes spends £3.5 million through Leo Burnett, which was appointed to handle its above-the-line account in February. Paddy Power's £4 million account is handled by Publicis, while William Hill spends £2.4 million with the Poulter agency in Leeds.