On 30 August 2021, he became the first ever Sri Lankan to win a gold medal at the Paralympics when he won the men's javelin throw F46 category.

[7] He attended the selection trial with the intention to participate at the 2012 Summer Paralympics and secured gold medal in a championship event held in Malaysia.

[14][15] He also claimed silver medal in men's 46 category at the 2019 World Para Athletics Championships by clearing a distance of 60.59 meters.

[29] He broke the F46 javelin throw world record which was previously held by India's Devendra Jhajharia when he claimed the gold medal.

Herath was wounded in Kilinochchi during the final stages of the brutal offensive operations to crush the LTTE on 16 December 2008 and retired from the Army on medical grounds at the age of 22.

[33][34] It was reported that three bullets had pierced his left arm which made him unable to engage in regular activities and was forced to spend his next four years at the Ragama Ranaviru Sevana for his treatment.

[38][39] On 30 August 2021, commander of the Sri Lankan Army Shavendra Silva promoted him as Warrant officer 1 with the approval of the Sri Lankan president Gotabaya Rajapaksa and secretary to the minister of defense Kamal Gunaratne following his gold medal triumph at the 2020 Summer Paralympics.