Ravaglia, 26, started 17 Serie A matches last season, keeping two clean sheets as Bologna finished eighth. He also made five Europa League appearances, notably saving a penalty from Morgan Rogers against Aston Villa.
Payero, 27, becomes Watford’s fourth signing from Udinese this summer. The midfielder began his career at Banfield before moving to Middlesbrough in 2021.
There, he scored in a penalty shootout victory over Manchester United in the FA Cup. He later spent a season with Boca Juniors before joining Udinese permanently in September 2023.
“Federico has valuable experience from playing in the top two divisions in Italy, and from playing in European competitions, that will really help us,” said Group Technical Director Gian Luca Nani.
“He is a goalkeeper of technique and talent, as well as being a leader in the dressing room and in organising the defence.”