Castello was born in Genoa, the son of a painter. After training in his native city he travelled to Milan and Parma, probably in the first half of the 1640s. His paintings from this period reflect the influence of Correggio and Parmigianino. He spent the rest of his brief career in Genoa where he particularly admired the work of Van Dyck, many of whose paintings could be seen in the city. Castello painted a number of frescoes in the palaces and churches of Genoa but his success was cut short by his early death in 1659.