Aubameyang was starting his first game of the season after recovering from coronavirusPierre-Emerick Aubameyang's hat-trick helped Arsenal to a welcome first win of the season as they beat a young West Bromwich Albion side to reach the Carabao Cup third round.
Aubameyang marked his first start of the season with two first-half tap-ins and a curling finish after the break.
He also acrobatically set up Nicolas Pepe for the third, with Bukayo Saka slotting in the Gunners' fourth.
Alexandre Lacazette came off the bench to fire in his side's sixth.
The win could have been even bigger too, with Martin Odegaard hitting the outside of the post from a tight angle and Pepe striking the bar with a chip.
West Brom fielded six debutants, five of them teenagers, but showed spirit right to the end on what was a difficult night for them.
The Baggies, who have made a superb start to this season under new boss Valerian Ismael, pressed high, got the ball forward quickly and would have taken an early lead had goalkeeper Aaron Ramsdale, on his Arsenal debut, not pushed Tom Fellows' whipped shot aside.
Even with the tie clearly decided they continued to carve out chances, with Taylor Gardner-Hickman twice denied by Ramsdale in the second half.
Ultimately, though, Arsenal - who now face AFC Wimbledon - were a class above, with the ruthless Aubameyang looking sharp after recovering from coronavirus.
He could hardly miss in scoring both of his first two goals, firstly following up Saka's saved shot to slot in before turning the ball in again after Pepe had hit the post.
His third was much harder to execute, but he did so with aplomb, curling in from 18 yards after cutting into the box.
With the Gabon striker among the goals, Pepe and Saka opening their own accounts for the season and Lacazette adding to the competition up front, Gunners boss Mikel Arteta can be more optimistic about facing Manchester City in the Premier League this coming weekend.
Arsenal manager Mikel Arteta: "When you lose a game, as quick as possible you have to win.
"Today's game is going to give us some confidence. We had players who played some first minutes.
"Auba [Aubameyang] after his Covid, to get some minutes and score three goals for his confidence is going to be great. Overall I think a really positive night.
On Aubameyang: "Obviously he is a really happy character and he needs that connection with people; with family, with friends, with fans.
"You could see the interaction when he left the pitch and I think that is something really positive for him, yes."
Arsenal striker Aubameyang, speaking to Sky Sports: "Great feeling. I'm happy we won this game. It's good to build confidence of the team.
"The commitment of every player is always there 100%. We try our best to give the fans what they want.
"This hopefully can give us something to build our confidence for the next games. We had to work hard and keep pushing.
"Everyone knows I like the space [in behind a defence]. My team-mates played very well. It was a good game today.
"We still have 36 games left so we will give our best for a good season."
Line-ups
West Brom
Formation 3-4-3
36Palmer
21Kipré33Taylor31Shotton
34Ingram32De Castro23Snodgrass20Reach
41Fellows9Zohore29Gardner-Hickman
36Palmer21Kipré33TaylorSubstituted forRichardsat 82'minutes31Shotton34Ingram32De CastroBooked at 2mins23SnodgrassSubstituted forKingat 74'minutes20Reach41Fellows9ZohoreSubstituted forFaalat 65'minutes29Gardner-HickmanSubstitutes
30Richards37Cann38King39Delaney40Faal42MalcolmArsenal
Formation 4-2-3-1
32Ramsdale
21Chambers16Holding31Kolasinac20Tavares
25Elneny34Xhaka
19Pépé8Ødegaard7Saka
14Aubameyang
32Ramsdale21Chambers16HoldingBooked at 27mins31KolasinacBooked at 39mins20Tavares25Elneny34XhakaSubstituted forLacazetteat 67'minutes19Pépé8ØdegaardSubstituted forMaitland-Nilesat 61'minutes7Saka14AubameyangSubstituted forMartinelliat 76'minutesSubstitutes
1Leno9Lacazette10Smith Rowe15Maitland-Niles22Marí23Sambi Lokonga35MartinelliReferee:David WebbAttendance:17,016Live Text
Match ends, West Bromwich Albion 0, Arsenal 6.
Second Half ends, West Bromwich Albion 0, Arsenal 6.
Offside, Arsenal. Sead Kolasinac tries a through ball, but Nicolas Pépé is caught offside.
Corner, Arsenal. Conceded by Adam Reach.
Foul by Nicolas Pépé (Arsenal).
Toby King (West Bromwich Albion) wins a free kick in the defensive half.
Bukayo Saka (Arsenal) wins a free kick in the defensive half.
Foul by Toby King (West Bromwich Albion).
Substitution, West Bromwich Albion. Rico Richards replaces Caleb Taylor because of an injury.
Attempt saved. Alexandre Lacazette (Arsenal) left footed shot from the centre of the box is saved in the bottom left corner.
Substitution, Arsenal. Gabriel Martinelli replaces Pierre-Emerick Aubameyang.
Substitution, West Bromwich Albion. Toby King replaces Robert Snodgrass.
Attempt missed. Nuno Tavares (Arsenal) right footed shot from outside the box misses to the left. Assisted by Nicolas Pépé.
Attempt saved. Taylor Gardner-Hickman (West Bromwich Albion) right footed shot from the right side of the box is saved in the bottom right corner. Assisted by Mo Faal.
Goal! West Bromwich Albion 0, Arsenal 6. Alexandre Lacazette (Arsenal) right footed shot from the centre of the box to the bottom right corner. Assisted by Nicolas Pépé.
Nuno Tavares (Arsenal) wins a free kick in the defensive half.
Foul by Ethan Ingram (West Bromwich Albion).
Nicolas Pépé (Arsenal) hits the bar with a left footed shot from the centre of the box. Assisted by Alexandre Lacazette with a through ball.
Substitution, Arsenal. Alexandre Lacazette replaces Granit Xhaka.
Substitution, West Bromwich Albion. Mo Faal replaces Kenneth Zohore.
