On the other side of the draw, Strasbourg pulled off a fine comeback to book their spot in the last four against Rayo Vallecano.
In Florence, Ismaila Sarr opened the scoring for Palace, before Albert Gudmundsson and Cher Ndour struck to give the Italian side hope.
It was a difficult night for Oliver Glasner’s side as a first defeat in six matches in all competitions was compounded by key men Adam Wharton and Maxence Lacroix both being forced off with knocks in the first half.
But most importantly the English club still remain in contention to add to their first-ever major trophy, the FA Cup won last season, in their maiden European campaign.
Ahead of kick-off, the Stadio Artemio Franchi held a minute’s silence for goalkeeper Alex Manninger, who died earlier Thursday aged 48 after his car was struck by a train. The Austrian spent a loan spell at Fiorentina in 2001-02.
Sarr gave Palace the start they wanted as Daniel Munoz stood the ball up for the Senegalese to head powerfully past David de Gea in the 17th minute.
The header took Sarr’s total in the Conference League this campaign to seven goals in 10 appearances.
Palace then offered Fiorentina a faint lifeline back into the tie just before the half-hour as Jaydee Canvot caught Rolando Mandragora in the box and Gudmundsson sent Dean Henderson the wrong way from the resulting spot-kick to get the hosts on the scoresheet.
The visitors’ nerves started to jangle considerably more inside the opening 10 minutes of the second half, as Ndour got the home fans rocking with a 30-yard strike that whistled into the bottom corner.
However, Palace managed to take the sting out of the tie and nullify Fiorentina as they progressed to a first European semi-final.
There they will face Ukrainians Shakhtar, who earlier drew 2-2 at AZ Alkmaar to progress 5-2 on aggregate. (AFP)
