The 27-year-old British singer recorded a reimagined version of the 1977 single with Guy Lawrence, a member of electronic music duo Disclosure.
"Highest song I've ever [expletive] sang. But a joy. I hope you all like it xx," Smith tweeted Thursday.
Smith, who publicly came out as gay in 2014 and as non-binary in 2017, said they consider "I Feel Love" an "anthem" in the LGBT community.
"As a queer person, 'I Feel Love' has followed me to every dance floor in every queer space from the minute I started clubbing," they wrote. "This song to me is an anthem of our community and it was an honour and most importantly so much fun to have a go at it."
Smith came to fame after appearing on Disclosure's 2012 single "Latch." They also collaborated with the duo on the 2015 single "Omen."
"I Feel Love" is Smith's first new single since "How Do You Sleep," released in July. Their most recent album, The Thrill of It All, debuted in November 2017.