The 29-year-old closed down Ben Foster after the goalkeeper received Daryl Janmaat’s pass and blocked the ball into the back of the Hornets’ net for his 18th league goal of the season.
The effort from the Gabon striker was enough to hand the Gunners their sixth away win this season despite their unconvincing performance in the tie and saw them return to the Premier League top-four.
Former England international Carragher disagrees with manager Unai Emery for failing to partner Aubameyang along with his strike partner Alexandre Lacazette in the encounter.
“I think Aubameyang was really brave,” Carragher told Sky Sports.
“Sometimes when you dangle that ankle out, and the keeper's in full stride clearing it, I think he was quite brave.
“He’s come in like a superstar from Borussia Dortmund. He doesn’t play every game, but for me, I still can’t believe he doesn’t play Aubameyang and Lacazette in away games, even against a 10-man Watford.”
Aubameyang has now scored 23 goals in all competitions this season and will hope to continue with his goalscoring form when Arsenal visit Napoli in their second leg Europa League quarter-final game on Thursday.