Mikel Arteta’s side were comfortable throughout, in what could have been a tricky away fixture, as Gabriel Martinelli, Kai Havertz, Gabriel, Saka and Leandro Trossard all scored.
The Gunners registered as many goals at Sporting as they managed in their previous eight Champions League away matches combined, in a result that lifts them to seventh in the table.
“We’ve shown the level we can play at,” Saka said.
“We know they haven’t lost here this season but we believed in ourselves.
“Everyone was top, I’m really proud of all the boys today.”
Martinelli tapped home from Jurrien Timber’s low cross as Arteta’s side went in front early on.
They doubled the lead in similar fashion, Saka getting in behind the Sporting defence and firing the ball across the box for Havertz to prod in from close range.
Gabriel scored his first Champions League goal on the stroke of half-time, powering in a header from a Declan Rice corner.
Shortly after the break Goncalo Inacio got a goal back for Sporting with a smart left-footed strike but it was a mere consolation for the hosts.
Ousmane Diomande was lucky to avoid a second yellow card when he went straight through the back of Martin Odegaard and conceded a penalty.
Saka scored the resulting spot-kick, whipping it into the bottom corner.
Mikel Merino’s fierce strike from the edge of the area was then parried by home goalkeeper Franco Israel into the path of Trossard, who headed into an empty net for Arsenal’s fifth.
Arteta spoke ahead of the match about wanting his players to make a Champions League statement by recording a big win against Sporting, and they duly obliged.
After the win, he said: “I’m very happy.
It’s a big result against a big opponent.
We wanted to make that statement.
“When you play in this competition against these teams you have to enjoy it.
What I loved about this team is the way that they flowed.
They played with purpose.
“If you want to be challenging for big trophies you have to be consistent.”
Martinelli’s goal, recorded at six minutes 43 seconds, was Arsenal’s fastest in the competition since Theo Walcott netted against Basel in September 2016 (06:42).
Saka was in fine form on the right wing, providing the assist for Arsenal’s second goal before converting from the spot as he registered his 11th goal involvement in the Champions League (six goals, five assists).
It is the second time that Arsenal have scored three goals in the first half of a Champions League away game, previously beating Galatasaray 4-1 in December 2014.
Arteta was able to withdraw key players Rice, Martinelli and Odegaard as his side cruised to a brilliant victory on the road.
The Gunners were winless in their last five away games in the competition (drawn two, lost three) but they blew Sporting away with their fast start and completely dominated from the first whistle.
Sporting’s last home match in the Champions League was a superb 4-1 win over Manchester City under former boss Ruben Amorim but there was no repeat of that performance against Arsenal.
The home side’s incredible unbeaten run of 17 wins and one draw in all competitions since the start of the season was ended in emphatic fashion by the north London side.
Viktor Gyokeres, who scored a hat-trick against City, was left frustrated as he failed to find a way past the Arsenal defence.
The Swedish striker fired a free-kick over the bar and had a strike from the edge of the area well saved by David Raya when he went through on goal.
Raya made several fine saves, tipping over teenager Geovany Quenda’s shot and getting down low to his left to push Morten Hjulmand’s strike past the post.
In stoppage time, Hjulmand had another strike tipped over the bar by Raya, who palmed away Conrad Harder’s effort from the resulting corner.
