In September 2019, Vunipola scored his first try for Saracens in a 2019–20 Premiership Rugby match against Wasps. In January 2020, Vunipola scored 17 points in a 2019–20 European Rugby Champions Cup pool stage match, as Saracens beat Ospreys 22–15. In the same month, referee Luke Pearce appointed Vunipola as Saracens captain, after Pearce decided he did not want to speak with Jackson Wray during a match against Harlequins. In a February 2020 Premiership Rugby match against Sale, Vunipola scored 17 points and won a man of the match award.