They've also created a video for the song that is premiering Monday on Vevo, and they'll perform it together live on Friday at the London Palladium for "Comic Relief — Face the Funny" on the BBC One television channel.TV
Their duet version of the song, which they recorded in Los Angeles earlier this year, is available for download as of Monday on iTunes and Google Play, and all profits will benefit Comic Relief's mission "to help change the lives of poor, vulnerable and disadvantaged people across the U.K. and Africa."
In a statement, Smith said, " 'Lay Me Down' holds a very special place in my heart, not only did I perform it at the Brits [the U.K.'s version of the Grammy Awards], I'm now going to perform it live on the Red Nose Day show with the extremely talented John Legend which is so exciting.
"I recently visited a Comic Relief funded project in my hometown which supports the young LGBT community in London," Smith said. "I'm extremely proud that my single will help raise money for projects like this and many others in the UK and across Africa."
Legend added, "We've been looking forward to working together for a while now. I'm so glad we could collaborate on such a great song and for such a great cause."
For Red Nose Day, which is held in the U.K. every two years, people are asked to wear red clown noses and raise awareness and money for those in need. The campaign is called "Make Your Face Funny for Money."