Operator Ladbrokes has withdrawn its operations in four European countries, following a 2014 regulatory operational review.
Customers in Russia, Finland, Portugal and Armenia will no longer be able to place bets with the UK bookmaker and were sent confirmation that their services would not be accepted.
The regulatory review looked into current legal situations and sought local advice on online gambling services in each country.
Ladbrokes is altering its focus to regulated European markets, following the withdrawal of its services in Hungary, Norway and Switzerland in 2014, which occurred after also pulling out of the Canadian market earlier in the year.
The Russian government signed in new measures to deter unlawful online gambling in December, which includes giving the Russian telecommunications state authority the power to block unlawful online gaming sites without a court order.
Romania and Portugal are set to define regulatory frameworks for online gambling in 2015, while Finland has stated that the market will continue to be controlled by its licensed gambling monopolies.
Ladbrokes has not confirmed whether it will re-enter those markets should they alter their online gaming frameworks.