Jessica Ellen Cornish (born 27 March 1988), known professionally as Jessie J, is an English singer and songwriter. Born and raised in London, she began her career on stage, aged 11, with a role in the West End musical Whistle Down the Wind. She studied at the BRIT School before signing with Gut Records and striking a songwriting deal with Sony/ATV Music Publishing.

After signing with Universal Republic, Jessie J came to prominence following the release of her debut single "Do It Like a Dude". Her next song "Price Tag" topped the charts in nineteen countries including the UK and was followed by the release of her debut album Who You Are (2011), which charted at number two in the UK. Other releases from the album included "Nobody's Perfect", "Who You Are", "Domino" and "Laserlight", which all charted within the top 10 in the UK Singles Chart, making Jessie J the first British female artist to have six top ten singles from a studio album. "Domino" also resulted in further international chart success, peaking at number six on the US Billboard Hot 100 and becoming her second number-one single in the UK. In 2012, Jessie J performed at the Queen's Diamond Jubilee Concert outside Buckingham Palace in June, as well as the closing ceremony of the 2012 Olympic Games in London on 12 August.

Her second album Alive (2013) reached the top 5 in the UK Albums Chart and also included the top-five hit songs "Wild" and "It's My Party". The release of her third album Sweet Talker (2014) was preceded by the single "Bang Bang" which debuted at number one in the UK and went multi-platinum worldwide. The album made the top 5 in the UK and reached number 10 on the US Billboard 200, her highest-charting album in the US. As of January 2015, Jessie J had sold over 20 million singles and 3 million albums worldwide.

Citing various influences, Jessie J is recognized for an unconventional musical and performance style that mixes soul vocals with contemporary R&B, pop, electropop, and hip-hop beats. Jessie J has garnered various awards and nominations for her music, including the 2011 Critics' Choice Brit Award and the BBC's Sound of 2011. Jessie J has supported various charitable causes, and has appeared on the UK charity telethons BBC Children in Need and Comic Relief. She has served as coach and mentor on the television shows The Voice UK and The Voice Australia.