The 28-year-old 'Bleeding Love' hitmaker shot to fame after winning the British version of the "X Factor" in 2006, reported Contactmusic.
Asked to choose between a global ban on vivisection and her singing career, Lewis replied that she would plump for the former.
"I would pick a global ban. I could still do my music in any capacity if I wanted to, but I think it's just so important for humans to show compassion."
Lewis, who supports several animal charities added, "They say you can judge a society on how it treats its animals, and I think that's very true - it all filters down."