Gavin and Stacey has been among the digital channel's biggest successesBBC Three is to be dropped from TV schedules and will move online, as part of the BBC's cost-cutting plans.
It means shows such as Don't Tell The Bride and Pramface will only be available through the iPlayer, rather than Freeview, satellite or cable.
The BBC will make an official announcement on Thursday, media correspondent David Sillito said.
Celebrities are already rallying behind the service. Matt Lucas said the move would be "really bad for new comedy".
The BBC's decision follows a speech given by director general Tony Hall last week, in which he said "tough choices" would have to be made if the corporation was to meet its savings target.
"We are in the final stages of a budget process to find an extra £100m of savings," he said at the Oxford Media Convention. "I will announce the outcome of those decisions in the next month."