The Grammy-winning crooner announced the cancellations on Tuesday in an Instagram post, following the first performance of his two-night gig in Sydney.
"I am deeply, deeply saddened to tell my Australian fans, I have to cancel my Australian tour," the pitch-transcending singer wrote.
"I have been vocally exhausted for a while now however last night in Sydney I had a small hemorrhage on my vocal chords. The doctors have told me I need to fully rest until my vocal chords have healed, otherwise this could become a huge long-term issue."
Smith, 22, apologized to those who bought tickets for the canceled leg of his "In the Lonely Hour" tour and said that he and his team would be announcing rearranged dates for December soon.
"This kills me," he wrote as the sign-off.
Fans left comments of support for the young breakout star all over social media and, in another post, Smith expressed his love.
"I love you all and I am so sorry x please keep your eye on my Facebook/Twitter/Instagram for re arranged December dates x," he wrote.
The "Stay With Me" singer was slated to perform again in Sydney on Tuesday then in Melbourne, Adelaide and Perth through May 4. On May 7, he's scheduled to perform in Tokyo.