The 27-year-old singer has become the newest judge on the show following her stint as a coach on the first two seasons of "The Voice UK".
Jessie posted photos of herself in hospital on Instagram, but TV producers have assured viewers that she will recover in time for the live shows, reported Contactmusic.
"We are sending our very best wishes for a speedy recovery to Jessie. We do not anticipate her illness impacting her return and we look forward to welcoming her back for the show in the coming months," Nine Network spokeswoman said.
"Being human sucks when you are non stop and your body says NOPE night right now. Unexpected but I'm here trying my best not to let it win (sic)," she said.
The Voice's season launch episode on Sunday, which was pre-recorded months ago, was its lowest opening night on Australian television but still topped the ratings.
