Duckadam started his career playing in the regional league of Arad county, before moving to UT Arad in 1978 to become professional. In 1982 played twice for Romania and, as a result, was signed by country giants FC Steaua Bucharest.
The Romanian goalkeeper leapt into the folklore of both the club and European competition by saving all four penalties taken by FC Barcelona during the shoot-out that won Steaua the European Champion Clubs' Cup on May 7, 1986, at the Estadio Ramón Sánchez Pizjuán in Seville. Duckadam became a hero by saving from José Ramón Alexanko, Angel Pedraza, 'Pichi' Alonso and Marcos Alonso. Only two of the eight penalties were converted as the Romanian side won the shoot-out 2-0 after 120 minutes of football had failed to produce a goal. Steaua won the main European trophy for the first time, and much of the credit for the surprise victory was given to Duckadam.
"I always had a dream about reaching a final and being the decisive player," said Duckadam in an exclusive interview for UEFA's 50 Years of European Club Football commemorative book. "In Seville l had the chance to turn the dream into reality. It was all down to me in the shoot-out. Alexanko took the first penalty. I chose to move to the right and he shot to the right and so I managed to save it. The second one was less simple. I tried to think like Pedraza. He would be thinking that when I’d made one save to the right then I would dive to my left. So he shot to the right and I managed to save the second penalty as well. The third one by Pichi Alonso was simpler. Any goalkeeper who has made two saves to his right is bound to go left for the third one. He shot to the right and I moved right again and saved the third one as well. With the fourth penalty I had a problem. I was seriously wondering what Marcos would do - whether he would copy the other three or shoot to the left. I decided to change side and moved to the left. Marcos also chose that side" - and that was how Helmut Duckadam saved four penalties.
On 25 March 2008, Duckadam was decorated by the president of Romania, with The Sportive Merit" Order class II, for his part in winning the of 1986 European Cup.