The Premier League club advanced 5-1 on aggregate to set up a May 28 title match against Real Betis, who prevailed in extra time for a 4-3 aggregate win over Fiorentina to reach their first European decider.
At Stamford Bridge on Thursday night, midfielder Kiernan Dewsbury-Hall collected a through ball from Tyrique George before scoring the winner with a low left-footed shot in the 38th minute.
"Amazing to be in the final," Dewsbury-Hall told TNT Sports.
"We set our sights at the start of the season to get as far as we can in this tournament and it has been a long couple of months but one more game to go and and hopefully we can lift that trophy."
Chelsea remain on course to become the first club to win all major European competitions.
The Blues have claimed the Champions League (2012, 2021), Europa League (2013, 2019), Cup Winners' Cup (1971, 1998) and Super Cup (1998, 2021).
The final takes place in Wroclaw, Poland.
"We have 20 days now to prepare the final," said Chelsea manager Enzo Maresca.
"Happy to face Betis ... I played four years for Seville, the big derby against Betis. We won a derby 1-0 and I scored the goal, so I know they don't love me.
"I met my wife in Seville, she's from Seville. My first son was born in Seville."
Maresca used only Marc Cucurella from the team that beat the new Premier League champions Liverpool 3-1 on Sunday.
Sixteen-year-old midfielder Reggie Walsh was given his first career start. When he was used as substitute in the first leg, he became the third youngest player for Chelsea, the club said.
In Florence, Antony crossed for substitute Abdessamad Ezzalzouli in the 97th minute to score past goalkeeper David De Gea for a 2-2 draw that sent Betis to the final.
Ezzalzouli also scored in the first-leg 2-1 victory in Spain last week.
Betis increased their aggregate lead from the first leg with a goal from Antony in the 30th. The midfielder, who is on loan from Manchester United, netted with a curling free kick that hit the post before bouncing into the net for his fourth goal in the competition.
Fiorentina's equaliser — on the evening — came four minutes later from a Robin Gosens header off a corner kick.
Gosens made it 3-3 on aggregate before the interval, heading home again from another corner.
Fiorentina were runners-up in the third-tier club competition in the last two years, losing finals to West Ham United in 2023 and Olympiacos last year.
With PA.
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