The musical's win for best live variety special on Sunday means Legend, Lloyd Webber and Rice have an Emmy to go with their Tonys, Grammys and their Oscars.
With his EGOT, he became the second African American member after Whoopi Goldberg.
Legend passed EGOT status over the weekend when he picked up an Emmy - along with Tim Rice and Andrew Lloyd Webber, also who turned EGOT - for their role as executive producers on the live television performance of the hit musical 'Jesus Christ Superstar'. He's previously won an Oscar for his work on the song "Glory" for the movie Selma, he earned his Tony for his work as the producer for the revival of the play Jitney, and he's been nominated for and won several Grammys over the years for his awesome music.
It's an important step forward in racial diversity in the arts community, and a monumental achievement for John Legend.
She captioned the video, "And I say hey, what a wonderful kind of day", referencing a popular internet joke that claims Legend looks like the animated TV aardvark, Arthur.
It took Legend 12 years to finish after he began with a Grammy win in 2006 for best new artist.
Andrew Lloyd Webber and Tim Rice never did a song with Common. Their "Christmas Story Live" number "In the Market for a Miracle", lost the Emmy for original music and lyrics to the "Saturday Night Live" song "Come Back, Barack".
Legend, 39, tied with "The Book of Mormon" and "Frozen" songwriter Robert Lopez, who had just turned 39 when he won all four awards, for being the youngest to complete the quadfecta, the BBC notes.