Nigeria forward Alex Iwobi was rested as a second string Arsenal side qualified for the semi-finals of the Carabao Cup by defeating West Ham 1-0 at the Emirates Stadium on Tuesday.
Welbeck, making his first start of competition this season, scored in the 42nd minute of the encounter.
It will be Arsenal’s first semi-final appearance in seven years.
The Gunners got the lead after a scrappy finish from Welbeck after Mathieu Debuchy nodded the ball into a dangerous position for him to fire in.
In the 60th minute, Aaron Cresswell’s curled freekick failed to threaten David Ospina in goal but as West Ham searched on for goal, David Moyes introduced Andy Carroll and Diafra Sakho.
Both players however could not get an equaliser to send the game into extra time.
The Hammers were lucky 14 minutes from time, that Joe Hart, back between the sticks after a four-game absence, was left off the hook after he brought down Welbeck outside the box but referee Kevin Friend show just a yellow card.