Trailing 3-0 from the first leg and never having beaten the Gunners in three previous meetings, Los Blancos had it all to do from minute one.
It was evident from the off that the hosts were up for the challenge, with Jude Bellingham making his 47th appearance in the competition, equalling the most by any player aged 21 or under (level with Iker Casillas), really in the mood.
Bellingham's international colleague, Myles-Lewis Skelly, became one of only three players aged 18 to start a knockout stage match away to Real in the Champions League, after Cesc Fabregas in February 2006 (Arsenal) and Max Meyer in March 2014 (FC Schalke 04).
Bukayo Saka failed to put the game to bed after ill-advised Panenka attempt
Though the hosts started on the front foot, Bukayo Saka had the chance to put the game to bed after just 12 minutes after Arsenal were awarded a penalty.
There were no claims from the visiting players, and only the intervention of VAR brought an infraction to official, Francois Letexier's attention. It was perhaps no surprise that he awarded the spot-kick, given that he had already awarded six penalties in seven UCL games this season, more than any other referee.
Saka's ill-advised attempt at a Panenka, saved by Thibaut Courtois - the first penalty miss in the UCL quarter-finals or later by an Arsenal player - sent close to 80,000 Real Madrid fans into ecstasy, but the hosts couldn't capitalise on the mistake.
Five minutes before half-time and Real Madrid's lauded attack still hadn't managed a shot on target, and that really shouldn't have come as any surprise to those watching given that in eight of their 14 games in the competition so far this season, no team had failed to score in the first half more often.
The hosts also attempted 23 crosses in the first half, their joint-most on record in a Champions League home match (since 2003/04), but completed just three.
Bellingham's six duels won in the opening 45 were the joint most of any player, and at least showed some commitment to the cause. His frustration at a lack of penetration in the Arsenal box and work ethic from his teammates was evidenced by his demeanour as the half wore on.
No way through solid Arsenal defence for Real Madrid
It wasn't until Vinicius Junior's shot (55:10) that Los Blancos managed a first effort on target, and just nine minutes later, Saka put the tie to bed with his fifth goal in this season's Champions League, more than any other Arsenal player.
Real will have known that the game was up at that point as Arsenal had a record of W7, D1, L0 when scoring the opening goal in the 24/25 competition.
Try as the hosts might, there was just no way through,h and William Saliba stood the tallest for the visitors, his 12 clearances the most by an Arsenal player in a Champions League match since Per Mertesacker v Bayern Munich in March 2014 (also 12).
Vinicius Junior's goal just two minutes after Saka's - coming as a result of an error from Saliba - was his eighth in this season's competition, his most in one edition of the tournament, and briefly gave the home support some belief.
It was also the Brazilian's 50th goal involvement in the UCL (29 goals, 21 assists), making him the third-quickest South American player to reach this milestone, after Neymar (52 games) and Lionel Messi (59 games).
Any thoughts the home support had regarding a late comeback soon wavered as the pattern of the game settled back down and Arsenal continued to ease through the gears.
Martinelli winner no more than Arsenal deserved after superb team performance
The significance of Luka Modric's substitute appearance may have gone under the radar for many, but it was his 134th as a Real outfield player, more European Cup/UEFA Champions League games than any other outfielder in club history, overtaking Karim Benzema (133).
He and his colleagues could do nothing about Gabriel Martinelli's injury-time winner for Mikel Arteta's men, however, and it was no more than the North Londoners deserved on another great UCL night for them.
Their qualification to the semi-final was just Arsenal's third (2005/06 and 2008/09 being the others), evidencing what an era-defining result this could be for Arteta and his squad.
They will face a marauding Paris Saint-Germain for a place in the final against either Internazionale or Barcelona, a final four worthy of such a prestigious competition, given that three of the quartet have either won their league already or are top of the table.
In hindsight, Real are likely to rue having to face English opposition in the knockout stages of the UCL, as they were also eliminated from the competition by Man City in 2019/20 and 2022/23, and Chelsea in 2020/21, meaning the last four times they've been knocked out has been by a Premier League side.
18 shots to Arsenal's 11 again shows the wastefulness that has been a feature from the likes of Kylian Mbappe et al in the bigger matches this season, and with 66.1% possession across the 90 minutes as well as an 86.1% pass completion statistic, it can't be said that Real didn't have the opportunity to turn things around.
Real Madrid's lauded attack failed to deliver on the big stage again
As with both El Clasico matches played so far this season, the big names in the team flattered to deceive and were, frankly, a huge disappointment.
Vinicius Junior was the only player to have more than 10 touches in the opposition box (15), with Mbappe and Rodrygo managing just four touches apiece inside Arsenal's penalty area. Even Lucas Vazquez had as many shots as Mbappe and Rodrygo combined (three).
Declan Rice was again the man making things happen for the visitors and, alongside Thomas Partey, formed a brick wall that Los Blancos weren't able to breach for the most part.
Indeed, Partey's 100% pass completion statistic (21 accurate passes from 21 attempted) and Rice's 96.2% (25 accurate passes from 26 attempted) tells its own story.
The one blemish for the Ghanaian was a regrettable late booking, which rules him out of the first leg of the semi-final against PSG.
That rush of blood to the head might well come back to haunt him and his team...
