The authors agree that the surname derives from a nickname related to gatto ("cat"). E. De Felice details that the motivations could be diverse: agility, flexibility, cunning or sly behaviour. R. Brondolo synthesises the origin with the expression "agile as a cat", and places it in northern Italy.

De Felice also notes that some variants derive from local place names: Gattai comes from Gattaia, in the province of Florence, and Gattei from Gatteo, in the Forlì area. As for the geographical distribution, he indicates that Gatti is frequent in Liguria and Lombardy; Gatto, in southern Italy; Gattolìn, in the Veneto; and Gattai and Gatteschi, in Tuscany.