Not much is known about Cosattini's early career. One of his few remaining works is the altarpiece of the church of Charity of Udine. It is a painting of the Holy Family. The painting has been dated to 1659. The painting reflects a link to Padovanino and, to some extent, Palma il Giovane, leading to the conjecture that Cosattini had at some point been an apprenticeship of the two painters or that he had closely followed their work and adopted it into his own style. Cosattini's close stylistic ties with Padovanino are further demonstrated in the seven paintings, thought to be made by Cosattini, that cover the main hall of the Uccellis College of Udine.