The singer was due to play the AO Arena tonight in Manchester but a statement confirmed she would not be able to play.
The Canadian-American singer-songwriter was set to take to the stage as part of her UK tour, but announced shortly after 6pm on Friday that she was unable to perform in Leeds - after doors had already opened.
In a message to her fans, Alanis said: "I feel so sad that I have to cancel tonight's show in Leeds.
"The entire range of my voice is gone today, I thought I could push through like we did last night.
"But it's gone. I love you and I am so sorry and I know I will see you again soon."
Ticket holders took to social media to express their disappointment.
However, the singer has now been forced to reschedule her planned show in Manchester tonight to June 30 due to illness.
Many fans in Leeds were left confused by the announcement and questioned the reasoning of not announcing a further Leeds show at the same time.
One said: "Wait, so the Manchester gig for Alanis Morissette has been rescheduled for this coming Thursday but the Leeds one has just been sacked off? Yikes."
Another added: "Why has Leeds not been rescheduled if Manchester has?"
Leeds First Direct Arena has been approached for comment.