The arrival of the Yellow Wall appeared to stun Chelsea from the start, but the East London side were right back into the Champions League tie at the break thanks to a brilliant finish from Raheem Sterling.
The Blues needed a lucky break in the first half, since attempts from Kai Havertz and Sterling seemed to hit the post more than the target, but the deadlock was broken after the winger rounded Marco Reus and smashed his effort into the net from five yards out.
A second half VAR decision gave Havertz a second chance - his first penalty rattled off the post yet again, but he calmly slotted home the retaken effort.
Chelsea saw the game out in the second half, which allows them to progress to the semi-finals, as they aim to build on their tournament win in 2020/21.
The Bundesliga side were unfortunate not to advance, but was hampered by injury. The Yellow Wall was the visitors' twelfth man tonight and the Germans will regroup - in no doubt - to go again.
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Story of the Match
A delay to the start of the match made no difference to the travelling Borussia Dortmund fans – they made their presence known from the off by unleashing a flare into Stamford Bridge.
With their noise, banners and flags, West London could have easily been confused with the North Rhineland.
Dortmund were forced into an early change, with Julian Brandt limping off the field after going down early. He was replaced by Giovanni Reyna, who impressed in the first half.
The American settled well even after not seeing much game time and his early cross rolled perfectly across goal, which created a perfect tap-in for a striker knock home - which was a key position that was missing for the German side.
The game settled after a period of back and forth, as Chelsea weathered Dortmund's opening aggressive attack.
Reus put Kepa to the test with a looping free-kick that the goalkeeper comfortably palmed away.
Dortmund were missing the offensive presence of Karim Adeyemi, who was absent due to injury. Many opportunities might have gone their way, as they lacked his pace and menace which he displayed in the first leg.
Chelsea's first notable attempt came from Havertz, whose shot bounced off the inside of the post.
Nobody knows how the ball did not bounce into the net off the woodwork, but he could only watch as his shot looped back behind the goalkeeper and went out for a goal kick.
However, the striker's second attempt was also disallowed. The German volleyed a rocket in off the crossbar, but the goal was disallowed because Sterling was offside in the build-up.
Everything was stacking up, and Chelsea had to break through eventually. Sterling ultimately broke the stalemate and levelled the game for the Blues.
He swung and missed Ben Chilwell's square ball the first time, but kept his cool to round Reus and smashed his second effort into the net.
Chelsea needed a lucky break since none of their offensive attempts was successful. Dortmund had been excellent until conceding - they had allowed the Blues to have shots on goal and were hugely bailed out by keeper Alexander Meyer.
The German side buckled beneath the pressure that Chelsea presented from the start.
Second Half
Chelsea pressed forward early in the second half and were awarded a penalty when Chilwell's cross deflected off Marius Wolf's arm. Havertz stepped up to take, but his first effort went begging.
The attacker looked to have magnets in his boots, as he sent Meyer the wrong way with a stuttering run-up, but his attempt struck the same post he hit not long before.
However, VAR observed Dortmund players entering the keeper's area before the kick was taken, allowing Havertz to retake.
He made no mistake this time, going to the right again, sending Meyer the wrong way and putting them in front!
Stamford Bridge erupted and the fans were bouncing – this was the first time their side had scored two goals in a game this year.
The wing-backs had given the hosts an additional edge out wide, which proved crucial against their visitors.
The return of Chilwell and Reece James together in the starting line-up - their sixth time starting together in six months - had made a significant impact on Chelsea's offensive options.
The home side remained under the cosh throughout the second half as Dortmund failed to provide any offensive threat.
Conor Gallagher had the ball in the back of the net and appeared to increase their lead, but the goal was waved out due to an offside ruling on Sterling – his third of the game.
After the final whistle, Graham Potter was serenaded by the home fans, and deservedly so - this is the greatest win of his stint as manager since succeeding Thomas Tuchel.
Player of the match – Raheem Sterling
Sterling was flagged for offside a couple of times in this game, but he was still useful in harassing Dortmund's defence every time he progressed up the pitch, in an attempt to improve their chances in front of goal.
The winger influenced Chelsea to attack into the heart of the Dortmund defence and benefitted from the return of Chilwell and James as wing-backs, who functioned as providers.
His 27th Champions League goal laid a solid platform for his team to build on throughout the game – and should be hopeful to bring this energy into the Premier League, as they aim to turn around their form.
