The pair, who collaborated on recent single 'Beneath Your Beautiful', will perform together on November 10 at Battersea Power Station for the Grey Goose Winter Ball to benefit the Elton John AIDS Foundation.
Sandé said: "My defining moment was really when I decided to take a step out of medicine.
"I can remember quite vividly sitting in a lecture theatre in Glasgow. I was looking around at everybody and how enthusiastic everybody was, taking notes - it was their passion to be there."
She added: "It was quite difficult. There was definitely people were telling me, 'If you just focus on medicine and give up this whole hobby of music'.
"You have to do what you believe in and you have to follow your instinct."
Labrinth said: "The defining moment in any artist's career is when the journey starts.
"When you've been slugging away, making countless records, all of them reside in your bedroom.
"And one day the world wants to know what's hiding in that little computer, what's hiding on your guitar, that was the defining moment for me."
Watch the Emeli Sandé and Labrinth 'Beneath Your Beautiful' video below: