The 37-year-old Australian presenter, who has hosted Nova 969's breakfast slot for ten years, announced on air on Wednesday morning that his last show will take place on September 2.
Watts thanked listeners for "an incredible ten years" and later paid tribute to his wife Georgie, saying: "[Without her,] there would be no jokes, there would be no laughter in me."
Fellow radio star Ben Fordham later wrote on his Twitter page: "Congrats to @MerrickWatts for a decade of breakfast radio at Nova. Mez has announced he's leaving next Friday. He's a good man."
Watts revealed last year that a health scare with his baby son Wolfe made him reassess his career.
"Wolfe was quite sick," he said. "It hit me for the first time that my job and career are so much less important to me than my son."
Watts used to host the morning show with Tim Ross until Ross announced his departure in 2009.
Soon after, there were reports of jealousy and tension between the pair, but both denied the rumours and insisted that they love each other like "brothers".
It is not yet known who will replace Watts on air.