Welbeck was then on the end of a superb team move that started with Bernd Leno and finished with Nacho Monreal crossing for the England worldwide to tap home from 10 yards to make it 2-0 shortly before half-time.
Brentford attacker Alan Judge would pull one back for the visitors in the 58th minute with a superb free-kick, although in-form frontman Alexandre Lacazette came off the bench to score a third goal in stoppage time to seal the win for Unai Emery's side.
Arsenal went 1-0 up in the fifth minute at the Emirates Stadium when Welbeck got his head to a corner kick from Matteo Guendouzi.
Emile Smith Rowe was impressive on his full debut for Arsenal
After heading the Gunners in front after four minutes, Welbeck rounded off a fine team move for the second before the interval. And Danny Welbeck is working with this commitment, and when he is playing with a performance like today, he is helping the team. Henrik Dalsgaard gave the Bees the lead after scoring in the first 44 seconds of the match, but the squad struggled to create scoring chances later in the match.
"I would rather have had Macclesfield at home but unfortunately we've got to travel to the Emirates which I'm sure all our supporters will be looking forward to", said Smith. "He gives us his quality and commitment every day", the Arsenal boss told his post-match press conference. "When I'm looking back [on the bench] I want to see a good player looking forward to help in the game for us".
He continued: "There are three things when we are speaking about an individual. The commitments of the players Aaron Ramsey and Danny Welbeck is very high". I know they are in the past year of their contracts and they are speaking with the club but for me the focus is only on the performance in each match.