John Terry was on the scoresheet for the Blues.
The tension in West London was palpable. The Blues had to overcome a one-goal deficit from the first leg a week earlier, where a somewhat subdued display saw them suffer a 1-0 defeat.
Juan Mata had put them ahead midway through the opening period before Vlad Chiriches leveled on the stroke of halftime.
Chelsea had to win by two clear goals on the night, and a John Terry header and Fernando Torres strike secured a 3-2 aggregate victory.
Rafa Benitez will be happy with the performance of his team, but how did the players perform individually? Bleacher Report looks at their performances in a little more detail.
One of Chelsea's most dependable players, Petr Cech, put on another accomplished display for the Blues on Thursday.
With Chelsea pushing forward throughout the game in search of the goals that would see them progress to the quarterfinal, it was inevitable Steaua Bucharest would enjoy the odd chance on the counter.
Whenever they did, they were met by the Czech stopper, who made a number of key saves.
It was another fine performance from Cech.
Ashley Cole was Chelsea's most accomplished defender on Thursday evening.
Now 32 years old, some have questioned whether he still has what it takes to justify his position in the Blues' lineup. On the evidence of this match, the Englishman certainly does.
Cole was instrumental going forward. But he was even better defensively, cutting out a number of Steaua attacks.
He's essential to this Chelsea team, and he was vital once again against Steaua.
His defensive teammates may have stolen the headlines with their exploits, but that's not to take the shine off David Luiz's performance against Steaua Bucharest.
The Brazilian put in a disciplined performance at the back, working well alongside John Terry. There were moments when he had to rein in his attacking instincts, but it demonstrated his maturity this term.
Steaua enjoyed few clear-cut opportunities at Stamford Bridge, and Luiz was a big reason for that.
He's made a habit of stepping up to the plate during his Chelsea career, and John Terry did it again versus Steaua Bucharest on Thursday evening.
With the scores level at 1-1 after the interval, the Chelsea captain's header early in the second half was vital as the Blues pulled their way back into this tie.
He didn't put a foot wrong defensively, dealing with the threat of Steaua alongside teammate David Luiz.
Filling in for Branislav Ivanovic at right-back, Cesar Azpilicueta enjoyed another comfortable display in the Chelsea back four.
Indeed, Ivanovic will be fearing for his place in the starting lineup if the Spaniard continues his impressive form.
As this Chelsea team develops in the coming months and seasons, one suspects Azpilicueta will an essential piece.
John Mikel Obi impressed once more on Thursday after coming off the bench to help Chelsea recover from 2-0 down against Manchester United at Old Trafford on Sunday,
Chelsea had to commit men forward in their hope of overturning their defeat against Steaua Bucharest. They did so safe in the knowledge Mikel was there to shield the back four.
It was a mature performance from the Nigerian who, in the past 12 months, has begun to deliver on the promise he showed as a youngster.
From Chelsea's perspective, long may that continue.
Playing alongside John Mikel Obi in the heart of midfield, Ramires was just as effective going forward for the Blues as he was with his defensive duties.
The Brazilian demonstrated that much against Manchester United in the FA Cup, and he repeated his form from Sunday at Stamford Bridge.
He may not have gotten on the scoresheet on Thursday, but he will be satisfied with his performance.
Eden Hazard demonstrated his value yet again, wreaking havoc in the Steaua Bucharest back line.
The young Belgian is enjoying a fine debut season in the Premier League. Steaua became another victim of his vast talents on Thursday as they struggled to cope.
With more performances like this from Hazard, there's no reason Chelsea cannot go all the way in the Europa League.
This was another Man of the Match display from Juan Mata. Mata scored Chelsea's opening goal and gained the assist for John Terry's vital header to make it 2-1 on the night against Steaua Bucharest,
It doesn't bear thinking to consider where Chelsea would be without their Spanish maestro who, despite a fine season last term, is looking better than ever.
His influence is considerable. The skill he demonstrated in evading his marker in the build-up to his opener just outlines the class he has at his disposal.
Mata oozes quality, and the Premier League is a better place for having him.
Completing Chelsea's three-pronged attack behind Fernando Torres on Thursday, Oscar is often lauded for his ability in possession.
But do not be fooled by his sleight frame and deft touch. Oscar can be just as effective with his defensive duties, and proved it against Steaua Bucharest.
He harassed, he harried and he was vital in breaking up and sniffing out any suggestion of danger high up the pitch.
Chelsea's "Three Amigos" helped the Blues press high—and Oscar was the most impressive at it.
Chelsea's record signing has come in for plenty of criticism since his £50 million transfer from Liverpool in January 2010.
But give credit where it's due; he looked sharp against Steaua Bucharest and his goal sent the Blues through to the quarterfinal, securing a 3-1 win on the night (3-2 on aggregate).
Sure, some doubters will still find flaws in his performance on Thursday and his missed penalty late on will not have helped his confidence, but it shouldn't take away from a positive display.
After coming on for Juan Mata in the dying stages, the Nigerian had little time to influence the game and helped the Blues see the tie out.
Another late change for Rafa Benitez in the 90th minute, Yossi Benayoun could have scored a surprise goal had he managed to latch on to a Fernando Torres cross with seconds remaining. With just a few minutes on the pitch, that was the most action he would see.