Blades will assume responsibility for expanding the international marketing team, developing a strong partner marketing programme and positioning 7digital as a leader in the digital music and content markets.
The appointment comes ahead of the digital music service's plans to expand its existing music and device strategy beyond the traditional a la carte download model.
"7digital is a well established name in the digital music world, and now is a great time to join the team. The company has ambitious growth plans for both its product portfolio and international footprint, and I'm looking forward to establishing 7digital as a leading digital music company at the global level."
7digital CEO Ben Drury added: "Kelaine is an ideal addition to the 7digital team. Our mobile offering has grown significantly over the past few years, and her experience will ensure this continues. We're about to expand our product offering too, so she is joining us at just the right time."
Blade will be based in 7digital's London HQ. The announcement follows a recent expansion of 7digital's international team, with senior appointments in the US earlier this month.