The 'I'm Yours' singer announced his engagement via Twitter late last year, revealing that he had successfully popped the question on December 23.
However, Mraz told The Daily Beast that he has now split from Prettyman, claiming that his heavy workload was the cause of the break-up.
"My greatest mistake right now is I've been clinging to my art," said Mraz. "In that, I have victory for my art and a great loss for my heart. At the moment, my beautiful fiancée is no longer my beautiful fiancée."
Mraz went on to say that the relationship ended amicably, and revealed that the two still attend yoga classes together.
"We are still super friends, we go to yoga together, we surf together. We acknowledge the journey that each of us is on," Mraz said.
The 33-year-old previously delayed his marriage, asserting that he would not wed Prettyman until gay marriage had been legalised.