Gioacchino Toesca was born in 1745 in Roma. He studied architecture as a student of Francesco Sabatini and at the age of 15, he moved to Madrid and later completed his studies in mathematics in Barcelona.
In 1780 he traveled to South America, to Santiago in the colonial Captaincy General of Chile at the request of the Royal Governor Agustín de Jáuregui and the Archbishop Santiago Manuel de Alday y Aspée, who engaged him to design the Catedral de Santiago de Chile (present day Santiago Metropolitan Cathedral).  In addition to this project he was also occupied in developing the plans for the Palacio de la Moneda to house the royal mint, which later became Chile's presidential palace.
Joaquín Toesca died in 1799 and did not live to see his two major projects, the Cathedral and the Palacio, completed. However, he did finish a number of other smaller works, including: the Cabildo de Santiago (city hall) of the Santiago Cabildo; the Hospital San Juan de Dios; and the tajamares (levees) which would prove crucial in protecting the city from the floods of the Mapocho River. His designs were generally in the neoclassical style of the period. His creative influence on Santiago—directly and through his many students—is notable.