The 200,000 member achievement was revealed on about an analyst roundtable meeting the company hosted this week. It reached its 100,000 one-year target after seven months in operation.
Blyk also claimed that a Millwards Brown study gave it the highest net advocacy score among "most" UK mobile networks (on a par with O2) and just behind Facebook and YouTube. Net advocacy is defined as those who would recommend the service minus those who would not.
It also claimed that its network is growing through word of month and six out of 10 people have joined because of a friend's recommendation.
Blog author Timo Ahopelto, who is head of strategy at Blyk, said: "Blyk and attending analysts yesterday discussed a major question on the industry's mind 'when will mobile advertising take off'?
"In our view, the industry will need to shift its focue from mobile and technology to media solutions that meet brands' communications goals while creating real value for the consumer."