The son of a stonecutter, Smyth was born in County Meath, Ireland.
Gandon employed Smyth as the sculptor to the Custom House, as well as for all of his Dublin projects.
In 1807, he carved the statues above the main entrance of the same building (which had been taken over by the Bank of Ireland) on College Green.
He carved the heads on the exterior of Johnston's Chapel Royal in Dublin Castle until his death, whereupon his son John continued the work.
[2] His son, John Smyth, was also a sculptor and succeeded him as Master of Modeling at the Dublin School.