A 3-2 victory on the night, 4-3 on aggregate, ensured that the Spanish giants were dumped out of the Europe and secures a memorable semi-final clash with West Ham for the German side.
A brace from Filip Kostic and an effort from Rafael Santos Borre gave Frankfurt a 3-0 lead on the night in Barcelona, before injury time efforts from Sergio Busquets and Memphis Depay set up a nervy ending for the visitors.
However the traveling fans were allowed to celebrate in style at the final whistle, creating quite a spectacle.
In unusual fashion, the German side brought around 30,000 supporters to Barcelona, meaning that almost half of the Nou Camp was filled with away fans.
As well as clearly inspiring their team to the most impressive of victories, the impact of the traveling support was very much felt by the home side.
Barcelona defender Eric Garcia said that it was 'strange' to have so many away fans in attendance, while Ronald Araujo insisted that the club would have to look into why so many away supporters were allowed into the stadium, something that was echoed by head coach Xavi Hernandez.
Quoted by Fichajes, he said: "It is evidence that the atmosphere has not helped us. This seemed like a final, with the field divided.
"The club is checking it. It was a miscalculation of ours, it is clear."
Speaking of the result, Xavi insisted that while Eintracht deserve credit for their victory, he's very disappointed with his side's inability to get the result needed to progress.
He said: "We have pulled the heroic, but insufficient.
"We have not played in the best way, we have not been well.
"They have gone well on the counterattack and have scored a great goal with a silly loss from us. Blow after blow. It is a very disappointing.
"It's a shame because we had hopes in this competition. Eintracht must be congratulated. They deserve it. We didn't know how to generate despite having control of the ball."
Asked if the result is a failure, Xavi added: "No, we have tried. You like the word failure a lot, but we don't see it that way.
"If there is failure, let there be learning, but I don't see it that way. It is a very big disappointment.
"The goal is to enter the Champions League and still alive."
But while Barcelona's exit from the competition is undoubtedly a huge upset, the story of the night has to be the German side.
With a semi-final clash with West Ham United to look forward to, the Bundesliga outfit will be hoping to showcase their outstanding support once again when they travel to London in search of a place in this year's Europa League final.