Smart received his positive test for COVID-19 on March 20, but announced good news on Sunday.
The 26-year-old wrote on Twitter: "Corona free as of two days ago. Cleared by Mass [Massachusetts] Dept of Health.
"Thanks for everyone's thoughts and prayers and I'm doing the same for everyone that's been affected by this.
"Stay safe and stay together – apart! Much love!"
There have been more than 722,000 cases of coronavirus worldwide, leading to over 33,900 deaths.
The United States have reported the most cases of any country – more than 142,000 – with over 2,400 deaths.