The former West Ham man – who bravely battled testicular cancer – converted from a Max Gradel on 65 minutes against DR Congo.
It means the Ivory Coast progress into the final on Sunday to play Nigeria, who beat South Africa on penalties in their final.
Match winner Haller switched international allegiances from France to Ivory Coast in 2020.
Two years later, he was diagnosed testicular cancer weeks only weeks after joining Borussia Dortumund from Ajax.
Haller felt unwell during training and went for medical examinations, which is when doctors discovered the tumour.
The 29-year-old underwent chemotheraphy and two operations at the end of 2022.
He then returned to action in January 2023 and has since made 36 appearances for the German side.
Haller has played in three AFCON games this year for host nation Ivory Coast as team-mate Franck Kessie stressed the home advantage.
Al-Ahli’s Kessie said: “As long as you still have a five or ten percent chance you need to keep believing, because that is what makes football beautiful.
“After the Morocco result we knew we had qualified and that changed everything.
“It gave us the strength we needed, it boosted us. We knew we couldn’t do worse than in the first round.
“We need to keep going like this because you can’t go all the way to the final only to then give up.”