Has there ever been a 9–0 in the Serie A?

Yes, 4 times.

The first time: October 13, 1929, AS Roma beat US Cremonese (AS Roma 9–0 US Cremonese).

The last time: February 18, 1951, AC Milan beat US Palermo (AC Milan 9–0 US Palermo), 75 years ago.

Home wins: 4. Away wins: 0.

Nearby scores

1. 10–0 1 time
2. 10–1 Never
3. 9–0 4 times
4. 9–1 8 times
5. 8–0 14 times
6. 8–1 4 times

All games

1. February 18, 1951 AC Milan 9–0 US Palermo
2. September 10, 1933 Internazionale 9–0 Casale
3. November 6, 1932 Torino FC 9–0 Casale
4. October 13, 1929 AS Roma 9–0 US Cremonese