The Brazil-born Italy international joined Hellas on loan from Fiorentina last summer, with the two clubs each owning 50 per cent of his registration.
The 27-year-old scored six goals in 32 Serie A appearances to help the Gialloblu finish 10th in 2013-14.
A statement from Hellas read: "Hellas Verona FC announces it has exercised their right to acquire the full sporting rights of Romulo Souza Orestes Caldeira from Fiorentina."
Romulo, who moved to La Viola from Cruzeiro three years ago, had been strongly linked with a move to AC Milan this summer.
He was included in Italy's 30-man preliminary World Cup squad for Brazil before being dropped from the final roster.