According to the Official Charts Company (OCC), Don’t Be So Hard on Yourself climbed 77 places to take the top spot.
It means Jess has matched the record for the most number ones from a female UK solo artist set by Cheryl Fernandez-Versini.
Jess' chart toppers include Rather Be (with Clean Bandit in Feb 2014), My Love (with Route 94 in March 2014), Hold My Hand (April 2015) and Not Letting Go (with Tinie Tempah in July 2015).
Jess said: ‘I can’t even begin to explain how awesome it feels to have Don’t Be So Hard On Yourself go to number one.’
‘The past few months have been one long, emotional journey so to come back to so much love and support is insanely amazing. I just want to say a massive thank you. This is the best feeling ever.’
Previous number one Marvin Gaye by Charlie Puth drops to number two and Calvin Harris and Disciples’ How Deep Is Your Love is at number three. The song is this week’s most streamed track for a second week, with 2.36 million plays.